Hyperkalemia: Difference between revisions
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{{Short description|Excess potassium in the blood}} |
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{{Infobox disease | |
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{{cs1 config|name-list-style=vanc}} |
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Name = Hyperkalemia | |
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{{Use dmy dates|date=July 2019}} |
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Image = K-TableImage.png | |
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{{Infobox medical condition (new) |
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Caption = [[potassium]] | |
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| name = Hyperkalemia |
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DiseasesDB = 6242 | |
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| synonyms = Hyperkalaemia |
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| image = ECG in hyperkalemia.svg |
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| caption = [[Electrocardiography]] showing [[precordial lead]]s in hyperkalemia. |
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ICDO = | |
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| pronounce = {{IPAc-en|ˌ|h|aɪ|p|ər|k|eɪ|ˈ|l|iː|m|i|ə}} |
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OMIM = | |
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| field = [[Critical care medicine]], [[nephrology]] |
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MedlinePlus = 001179 | |
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| symptoms = [[Palpitations]], [[muscle pain]], [[muscle weakness]], [[paresthesia|numbness]]<ref name=Leh2011/><ref name=BMJ2015/> |
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eMedicineSubj = emerg | |
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| complications = [[Cardiac arrest]]<ref name=Leh2011/><ref name=EU2010/> |
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eMedicineTopic = 261 | |
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| onset = |
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| duration = |
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| types = |
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| causes = [[Kidney failure]], [[hypoaldosteronism]], [[rhabdomyolysis]], certain medications<ref name=Leh2011/> |
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| risks = |
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| diagnosis = Blood potassium > 5.5{{nbsp}}mmol/L, [[electrocardiogram]]<ref name=EU2010/><ref name=Pat2006/> |
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| differential = [[Pseudohyperkalemia]]<ref name=Leh2011/><ref name=BMJ2015/> |
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| prevention = |
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| treatment = Medications, low potassium diet, [[hemodialysis]]<ref name=Leh2011/> |
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| medication = [[Calcium gluconate]], [[dextrose]] with [[insulin]], [[salbutamol]], [[sodium bicarbonate]]<ref name=Leh2011/><ref name=EU2010/><ref name=Sm2005/> |
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| prognosis = |
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| frequency = ~2% (people in hospital)<ref name=BMJ2015/> |
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| deaths = |
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}} |
}} |
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<!-- Definition and symptoms --> |
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'''Hyperkalemia''' (''hyper-'' high; ''kalium'', potassium; ''-emia'', "in the blood") is an elevated blood level of the [[electrolyte]] [[potassium]]. Extreme hyperkalemia is a [[medical emergency]] due to the risk of potentially fatal abnormal heart rhythms ([[arrhythmia]]). |
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'''Hyperkalemia''' is an elevated level of [[potassium]] (K<sup>+</sup>) in the [[Serum (blood)|blood]].<ref name=Leh2011/> Normal potassium levels are between 3.5 and 5.0{{nbsp}}[[Molar concentration|mmol/L]] (3.5 and 5.0{{nbsp}}[[Equivalent (chemistry)|mEq/L]]) with levels above 5.5{{nbsp}}mmol/L defined as hyperkalemia.<ref name=EU2010/><ref name="Pat2006">{{Cite book |last=Pathy |first=M.S. John |title=Principles and practice of geriatric medicine |date=2006 |publisher=Wiley |isbn=9780470090558 |edition=4th |volume=2 |location=Chichester [u.a.] |page=Appendix |chapter=Appendix 1: Conversion of SI Units to Standard Units |doi=10.1002/047009057X.app01}}</ref> Typically hyperkalemia does not cause symptoms.<ref name=Leh2011/> Occasionally when severe it can cause [[palpitations]], [[muscle pain]], [[muscle weakness]], or [[paresthesia|numbness]].<ref name=Leh2011/><ref name=BMJ2015/> Hyperkalemia can cause an [[Heart arrhythmia|abnormal heart rhythm]] which can result in [[cardiac arrest]] and death.<ref name=Leh2011/><ref name=EU2010/> |
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<!-- Cause and diagnosis --> |
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Common causes of hyperkalemia include [[kidney failure]], [[hypoaldosteronism]], and [[rhabdomyolysis]].<ref name="Leh2011">{{Cite journal |last=Lehnhardt |first=Anja |last2=Kemper |first2=Markus J. |date=March 2011 |title=Pathogenesis, diagnosis and management of hyperkalemia |journal=Pediatric Nephrology |volume=26 |issue=3 |pages=377–384 |doi=10.1007/s00467-010-1699-3 |pmc=3061004 |pmid=21181208}}</ref> A number of medications can also cause high blood potassium including [[spironolactone]], [[Nonsteroidal anti-inflammatory drug|NSAIDs]], and [[angiotensin converting enzyme inhibitors]].<ref name=Leh2011/> The severity is divided into mild (5.5–5.9{{nbsp}}mmol/L), moderate (6.0–6.4{{nbsp}}mmol/L), and severe (>6.5{{nbsp}}mmol/L).<ref name="EU2010">{{Cite journal |last=Soar |first=Jasmeet |last2=Perkins |first2=Gavin D. |last3=Abbas |first3=Gamal |last4=Alfonzo |first4=Annette |last5=Barelli |first5=Alessandro |last6=Bierens |first6=Joost J.L.M. |last7=Brugger |first7=Hermann |last8=Deakin |first8=Charles D. |last9=Dunning |first9=Joel |last10=Georgiou |first10=Marios |last11=Handley |first11=Anthony J. |last12=Lockey |first12=David J. |last13=Paal |first13=Peter |last14=Sandroni |first14=Claudio |last15=Thies |first15=Karl-Christian |date=October 2010 |title=European Resuscitation Council Guidelines for Resuscitation 2010 Section 8. Cardiac arrest in special circumstances: Electrolyte abnormalities, poisoning, drowning, accidental hypothermia, hyperthermia, asthma, anaphylaxis, cardiac surgery, trauma, pregnancy, electrocution |journal=Resuscitation |volume=81 |issue=10 |pages=1400–1433 |doi=10.1016/j.resuscitation.2010.08.015 |pmid=20956045 |last16=Zideman |first16=David A. |last17=Nolan |first17=Jerry P.}}</ref> High levels can be detected on an [[Electrocardiography|electrocardiogram]] (ECG).<ref name=EU2010/> Pseudohyperkalemia, due to breakdown of [[Cell (biology)|cell]]s during or after taking the blood sample, should be ruled out.<ref name=Leh2011/><ref name="BMJ2015">{{Cite journal |last=McDonald |first=Timothy J |last2=Oram |first2=Richard A |last3=Vaidya |first3=Bijay |date=20 October 2015 |title=Investigating hyperkalaemia in adults |journal=BMJ |volume=351 |pages=h4762 |doi=10.1136/bmj.h4762 |pmid=26487322 |s2cid=206907572}}</ref> |
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<!-- Treatment --> |
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Initial treatment in those with ECG changes is salts, such as [[calcium gluconate]] or [[calcium chloride]].<ref name=Leh2011/><ref name=EU2010/> Other medications used to rapidly reduce blood potassium levels include [[insulin]] with [[Glucose|dextrose]], [[salbutamol]], and [[sodium bicarbonate]].<ref name="Leh2011" /><ref name="Sm2005">{{Cite journal |last=Mahoney |first=Brian A |last2=Smith |first2=Willard AD |last3=Lo |first3=Dorothy |last4=Tsoi |first4=Keith |last5=Tonelli |first5=Marcello |last6=Clase |first6=Catherine |date=20 April 2005 |title=Emergency interventions for hyperkalaemia |journal=Cochrane Database of Systematic Reviews |volume=2005 |issue=2 |pages=CD003235 |doi=10.1002/14651858.CD003235.pub2 |pmc=6457842 |pmid=15846652}}</ref> Medications that might worsen the condition should be stopped and a low potassium diet should be started.<ref name=Leh2011/> Measures to remove potassium from the body include diuretics such as [[furosemide]], potassium-binders such as [[polystyrene sulfonate]] (Kayexalate) and [[sodium zirconium cyclosilicate]], and [[hemodialysis]].<ref name=Leh2011/> Hemodialysis is the most effective method.<ref name=EU2010/> |
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<!-- Epidemiology and culture --> |
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Hyperkalemia is rare among those who are otherwise healthy.<ref name=Kov2016/> Among those who are hospitalized, rates are between 1% and 2.5%.<ref name=BMJ2015/> It is associated with an increased mortality, whether due to hyperkalaemia itself or as a marker of severe illness, especially in those without [[chronic kidney disease]].<ref>{{Cite journal |last=Einhorn |first=Lisa M. |last2=Zhan |first2=Min |last3=Hsu |first3=Van Doren |last4=Walker |first4=Lori D. |last5=Moen |first5=Maureen F. |last6=Seliger |first6=Stephen L. |last7=Weir |first7=Matthew R. |last8=Fink |first8=Jeffrey C. |date=22 June 2009 |title=The Frequency of Hyperkalemia and Its Significance in Chronic Kidney Disease |journal=Archives of Internal Medicine |volume=169 |issue=12 |pages=1156–1162 |doi=10.1001/archinternmed.2009.132 |pmc=3544306 |pmid=19546417}}</ref><ref name="Kov2016">{{Cite journal |last=Kovesdy |first=Csaba P |date=March 2017 |title=Updates in hyperkalemia: Outcomes and therapeutic strategies |journal=Reviews in Endocrine and Metabolic Disorders |volume=18 |issue=1 |pages=41–47 |doi=10.1007/s11154-016-9384-x |pmc=5339065 |pmid=27600582}}</ref> The word ''hyperkalemia'' comes from ''hyper-'' 'high' + ''kalium'' 'potassium' + [[List of medical roots, suffixes and prefixes|''-emia'' 'blood condition']].<ref>{{Cite book |last=Cohen |first=Barbara J |url=https://books.google.com/books?id=SEOQXdrlt9wC&pg=PA326 |title=Medical Terminology: An Illustrated Guide |last2=DePetris |first2=Ann |date=2013 |publisher=Lippincott Williams & Wilkins |isbn=9781451187564 |page=326 |archive-url=https://web.archive.org/web/20170908183104/https://books.google.com/books?id=SEOQXdrlt9wC&pg=PA326 |archive-date=2017-09-08 |url-status=live}}</ref><ref>{{Cite book |last=Herlihy |first=Barbara |url=https://books.google.com/books?id=uX6zAQAAQBAJ&pg=PA487 |title=The Human Body in Health and Illness |date=2014 |publisher=Elsevier Health Sciences |isbn=9781455756421 |page=487 |archive-url=https://web.archive.org/web/20170908183104/https://books.google.com/books?id=uX6zAQAAQBAJ&pg=PA487 |archive-date=2017-09-08 |url-status=live}}</ref> |
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==Signs and symptoms== |
==Signs and symptoms== |
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The symptoms of an elevated potassium level are generally few and nonspecific.<ref name="NKF2020">{{Cite web |date=8 February 2016 |title=What is Hyperkalemia? |url=https://www.kidney.org/atoz/content/what-hyperkalemia |access-date=23 February 2020 |website=National Kidney Foundation}}</ref> Nonspecific symptoms may include feeling tired, numbness and weakness.<ref name=NKF2020/> Occasionally [[palpitations]] and shortness of breath may occur.<ref name=NKF2020/><ref name="symptoms-mayo">{{Cite web |date=2011-11-18 |title=High potassium (hyperkalemia) |url=http://www.mayoclinic.org/symptoms/hyperkalemia/basics/when-to-see-doctor/sym-20050776 |url-status=live |archive-url=https://web.archive.org/web/20140228150609/http://www.mayoclinic.org/symptoms/hyperkalemia/basics/when-to-see-doctor/sym-20050776 |archive-date=2014-02-28 |access-date=2014-02-28 |publisher=Mayo Clinic}}</ref><ref>{{Cite web |date=8 February 2016 |title=What is Hyperkalemia? |url=https://www.kidney.org/atoz/content/what-hyperkalemia |access-date=25 June 2019 |website=[[National Kidney Foundation]] (NKF)}}</ref> Hyperventilation may indicate a compensatory response to [[metabolic acidosis]], which is one of the possible causes of hyperkalemia.<ref name="Kovesdy2015">{{Cite journal |last=Kovesdy |first=CP |date=December 2015 |title=Management of Hyperkalemia: An Update for the Internist |journal=The American Journal of Medicine |volume=128 |issue=12 |pages=1281–7 |doi=10.1016/j.amjmed.2015.05.040 |pmid=26093176}}</ref> Often, however, the problem is detected during screening [[blood test]]s for a medical disorder, or after hospitalization for complications such as [[cardiac arrhythmia]] or [[sudden cardiac death]]. High levels of potassium (> 5.5{{nbsp}}mmol/L) have been associated with cardiovascular events.<ref name="Kovesdy2015" /> |
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Symptoms are fairly nonspecific and generally include [[malaise]], [[palpitations]] and [[muscle weakness]]; mild hyperventilation may indicate a compensatory response to [[metabolic acidosis]], which is one of the possible causes of hyperkalemia. Often, however, the problem is detected during screening [[blood test]]s for a medical disorder, or it only comes to medical attention after complications have developed, such as [[cardiac arrhythmia]] or [[Cardiac arrest|sudden death]]. |
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==Causes== |
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During the medical history taking, a physician will dwell on [[Nephrology|kidney disease]] and [[medication]] use (see below), as these are the main causes. The combination of [[abdominal pain]], [[hypoglycemia]] and [[hyperpigmentation]], often in the context of a history of other [[Autoimmune diseases|autoimmune disorders]], may be signs of [[Addison's disease]], itself a medical emergency. |
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===Ineffective elimination=== |
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==Diagnosis== |
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[[Chronic kidney disease|Decreased kidney function]] is a major cause of hyperkalemia. This is especially pronounced in [[acute kidney injury]] where the glomerular filtration rate and tubular flow are markedly decreased, characterized by [[oliguria|reduced urine output]].<ref name="Kovesdy2015" /> This can lead to a dramatically elevated potassium in conditions of increased cell breakdown as the potassium is released from the cells and cannot be eliminated in the kidney. In [[chronic kidney disease]], hyperkalemia occurs as a result of reduced aldosterone responsiveness and reduced sodium and water delivery in distal tubules.<ref name="UpToDate causes and evaluation" /> |
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In order to gather enough information for diagnosis, the measurement of potassium needs to be repeated, as the elevation can be due to [[hemolysis]] in the first sample. The normal serum level of potassium is 3.5 to 5 mEq/L. Generally, blood tests for [[renal function]] ([[creatinine]], [[blood urea nitrogen]]), [[glucose]] and occasionally [[creatine kinase]] and [[cortisol]] will be performed. Calculating the [[trans-tubular potassium gradient]] can sometimes help in distinguishing the cause of the hyperkalemia. |
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Medications that interfere with urinary excretion by inhibiting the [[renin–angiotensin system]] is one of the most common causes of hyperkalemia. Examples of medications that can cause hyperkalemia include [[ACE inhibitor]]s, [[angiotensin II receptor antagonist|angiotensin receptor blockers]],<ref name="Kovesdy2015" /> non-selective [[beta blocker]]s, and [[calcineurin inhibitor]] immunosuppressants such as [[ciclosporin]] and [[tacrolimus]].<ref>{{Cite journal |last=Hwa Lee |first=Chang |last2=Ho Kim |first2=Gheun |date=31 December 2007 |title=Electrolyte and Acid-Base Disturbances Induced by Clacineurin Inhibitors |journal=Electrolyte Blood Press |volume=5 |issue=2 |pages=126–130 |doi=10.5049/EBP.2007.5.2.126 |pmc=3894512 |pmid=24459511 |quote=Cyclosporine may reduce potassium excretion by altering the function of several transporters, decreasing the activity of the renin-angiotensin-aldosterone system, and impairing tubular responsiveness to aldosterone}}</ref> For potassium-sparing [[diuretic]]s, such as [[amiloride]] and [[triamterene]]; both the drugs block epithelial sodium channels in the collecting tubules, thereby preventing potassium excretion into urine.<ref name="UpToDate causes and evaluation" /> [[Spironolactone]] acts by competitively inhibiting the action of aldosterone.<ref name="Kovesdy2015" /> [[Non-steroidal anti-inflammatory drugs|NSAIDs]] such as [[ibuprofen]], [[naproxen]], or [[Celebrex|celecoxib]] inhibit [[prostaglandin]] synthesis, leading to reduced production of renin and aldosterone, causing potassium retention.<ref>{{Cite journal |last=Kim |first=Sejoong |last2=Joo |first2=KW |date=31 December 2007 |title=Electrolyte and Acid-Base Disturbances Associated with Non-Steroidal Anti-Inflammatory Drugs |journal=Electrolyte Blood Press |volume=5 |issue=2 |pages=116–125 |doi=10.5049/EBP.2007.5.2.116 |pmc=3894511 |pmid=24459510}}</ref> The antibiotic [[trimethoprim]] and the [[Antihelminthic|antiparasitic medication]] [[pentamidine]] inhibits potassium excretion, which is similar to mechanism of action by amiloride and triamterene.<ref>{{Cite journal |last=Karet |first=Fiona E. |date=February 2009 |title=Mechanisms in Hyperkalemic Renal Tubular Acidosis: Figure 1. |journal=Journal of the American Society of Nephrology |volume=20 |issue=2 |pages=251–254 |doi=10.1681/ASN.2008020166 |pmid=19193780 |doi-access=free}}</ref> |
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In many cases, [[medical ultrasonography|renal ultrasound]] will be performed, since hyperkalemia is highly suggestive of renal failure. |
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[[Mineralocorticoid]] (aldosterone) deficiency or resistance can also cause hyperkalemia. Primary adrenal insufficiency are: [[Addison's disease]]<ref>{{Cite web |last=B Mount |first=David |last2=H Sterns |first2=Richard |last3=Lacroix |first3=Andre |last4=Forman P |first4=John |title=Hyponatremia and hyperkalemia in adrenal insufficiency |url=https://www.uptodate.com/contents/hyponatremia-and-hyperkalemia-in-adrenal-insufficiency |url-access=subscription |access-date=6 October 2017 |publisher=UpToDate}}</ref> and [[congenital adrenal hyperplasia|congenital adrenal hyperplasia (CAH)]] (including enzyme deficiencies such as [[Congenital adrenal hyperplasia due to 21-hydroxylase deficiency|21α hydroxylase]], [[Congenital adrenal hyperplasia due to 17α-hydroxylase deficiency|17α hydroxylase]], [[Congenital adrenal hyperplasia due to 11β-hydroxylase deficiency|11β hydroxylase]], or [[Congenital adrenal hyperplasia due to 3β-hydroxysteroid dehydrogenase deficiency|3β dehydrogenase]]).<ref>{{Cite web |last=F Young |first=William |last2=H Sterns |first2=Richard |last3=Forman |first3=John P |title=Etiology, diagnosis, and treatment of hypoaldosteronism (type 4 RTA) |url=https://www.uptodate.com/contents/etiology-diagnosis-and-treatment-of-hypoaldosteronism-type-4-rta |url-access=subscription |access-date=12 October 2017 |website=UpToDate |quote=In children, hypoaldosteronism can result from a deficiency of enzymes required for aldosterone synthesis}}</ref> |
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Also, [[electrocardiography]] (EKG/ECG) may be performed to determine if there is a significant risk of cardiac [[arrhythmias]] (see [[#ECG/EKG Findings|ECG/EKG Findings]], below). |
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* Type IV [[renal tubular acidosis]] (aldosterone resistance of the kidney's tubules) |
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* Gordon's syndrome ([[pseudohypoaldosteronism]] type II) ("familial hypertension with hyperkalemia"), a rare genetic disorder caused by defective modulators of salt transporters, including the [[Sodium-chloride symporter|thiazide-sensitive Na-Cl cotransporter]]. |
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===Excessive release from cells=== |
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==Differential diagnosis== |
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[[Metabolic acidosis]] can cause hyperkalemia as the elevated hydrogen ions in the cells can displace potassium, causing the potassium ions to leave the cell and enter the bloodstream. However, in [[respiratory acidosis]] or organic acidosis such as [[lactic acidosis]], the effect on serum potassium are much less significant although the mechanisms are not completely understood.<ref name="UpToDate causes and evaluation" /> |
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Insulin deficiency can cause hyperkalemia as the [[hormone]] [[insulin]] increases the uptake of potassium into the cells. Hyperglycemia can also contribute to hyperkalemia by causing [[Renal physiology|hyperosmolality]] in extracellular fluid, increasing water diffusion out of the cells and causes potassium to move alongside water out of the cells also. The co-existence of insulin deficiency, hyperglycemia, and hyperosmolality is often seen in those affected by [[diabetic ketoacidosis]]. Apart from diabetic ketoacidosis, there are other causes that reduce insulin levels such as the use of the medication [[octreotide]], and fasting which can also cause hyperkalemia. Increased tissue breakdown such as [[rhabdomyolysis]], [[burn]]s, or any cause of rapid tissue [[necrosis]], including [[tumor lysis syndrome]] can cause the release of intracellular potassium into blood, causing hyperkalemia.<ref name="Kovesdy2015" /><ref name="UpToDate causes and evaluation" /> |
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Causes include: |
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[[Beta2-adrenergic agonist]]s act on beta-2 receptors to drive potassium into the cells. Therefore, [[beta blocker]]s can raise potassium levels by blocking beta-2 receptors. However, the rise in potassium levels is not marked unless there are other co-morbidities present. Examples of drugs that can raise the serum potassium are non-selective beta-blockers such as [[propranolol]] and [[labetalol]]. Beta-1 selective blockers such as [[metoprolol]] do not increase serum potassium levels.<ref name="UpToDate causes and evaluation" />{{medcn|date=August 2019}} |
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=== Ineffective elimination from the body=== |
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* [[Renal insufficiency]] |
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* [[Medication]] that interferes with urinary excretion: |
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** [[ACE inhibitor]]s and [[angiotensin II receptor antagonist|angiotensin receptor blockers]] |
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** Potassium-sparing [[diuretic]]s (e.g. [[amiloride]] and [[spironolactone]]) |
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** [[Non-steroidal anti-inflammatory drugs|NSAIDs]] such as [[ibuprofen]], [[naproxen]], or [[Celebrex|celecoxib]] |
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** The [[Immunosuppressive drug#Drugs acting on immunophilins|calcineurin inhibitor]] immunosuppressants [[ciclosporin]] and [[tacrolimus]] |
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** The antibiotic [[trimethoprim]] |
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** The antiparasitic drug [[pentamidine]] |
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* [[Mineralocorticoid]] deficiency or resistance, such as: |
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** [[Addison's disease]] |
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** [[Hypoaldosteronism|Aldosterone deficiency]], including reduced levels due to the blood thinner, [[heparin]] |
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** Some forms of [[congenital adrenal hyperplasia]] |
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** Type IV [[renal tubular acidosis]] (resistance of renal tubules to aldosterone) |
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* [[Gordon's syndrome]] (“familial hypertension with hyperkalemia”), a rare genetic disorder caused by defective modulators of salt transporters, including the [[thiazide-sensitive Na-Cl cotransporter]]. |
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Exercise can cause a release of potassium into bloodstream by increasing the number of potassium channels in the cell membrane. The degree of potassium elevation varies with the degree of exercise, which range from 0.3 meq/L in light exercise to 2 meq/L in heavy exercise, with or without accompanying ECG changes or lactic acidosis. However, peak potassium levels can be reduced by prior physical conditioning and potassium levels are usually reversed several minutes after exercise.<ref name="UpToDate causes and evaluation" /> High levels of [[adrenaline]] and [[Norepinephrine|noradrenaline]] have a protective effect on the cardiac electrophysiology because they bind to beta 2 adrenergic receptors, which, when activated, extracellularly decrease potassium concentration.<ref>{{Cite journal |last=Lindinger MI |date=April 1995 |title=Potassium regulation during exercise and recovery in humans: implications for skeletal and cardiac muscle |journal=J. Mol. Cell. Cardiol. |volume=27 |issue=4 |pages=1011–1022 |doi=10.1016/0022-2828(95)90070-5 |pmid=7563098}}</ref> |
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=== Excessive release from cells=== |
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* [[Rhabdomyolysis]], [[burn (injury)|burns]] or any cause of rapid tissue [[necrosis]], including [[tumor lysis syndrome]] |
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* Massive [[blood transfusion]] or massive [[hemolysis]] |
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* Shifts/transport out of cells caused by [[acidosis]], low [[insulin]] levels, [[beta-blocker]] therapy, [[digoxin]] overdose, or the paralyzing agent [[succinylcholine]] |
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[[Hyperkalemic periodic paralysis]] is an [[Dominance (genetics)|autosomal dominant]] clinical condition where there is a mutation in gene located at 17q23 that regulates the production of protein [[Nav1.4|SCN4A]]. SCN4A is an important component of [[sodium channel]]s in skeletal muscles. During exercise, sodium channels would open to allow influx of sodium into the muscle cells for [[depolarization]] to occur. But in hyperkalemic periodic paralysis, sodium channels are slow to close after exercise, causing excessive influx of sodium and displacement of potassium out of the cells.<ref name="UpToDate causes and evaluation" /><ref>{{Cite web |last=Gutmann |first=Laurie |last2=Conwit |first2=Robin |last3=M shefner |first3=Jeremy |last4=L Wilterdink |first4=Janet |title=Hyperkalemic periodic paralysis |url=https://www.uptodate.com/contents/hyperkalemic-periodic-paralysis?source=see_link§ionName=PATHOGENESIS&anchor=H3#H3 |url-access=subscription |access-date=3 October 2017 |publisher=UpToDate}}</ref> |
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=== Excessive intake=== |
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* [[Intoxication]] with salt-substitute, potassium-containing dietary supplements, or [[potassium chloride]] (KCl) infusion. Note that for a person with normal kidney function and nothing interfering with normal elimination (see above), hyperkalemia by potassium intoxication would be seen only with large infusions of KCl or oral doses of several hundred millequivalents of KCl.<ref>{{cite journal |author=Su M, Stork C, Ravuri S, ''et al.'' |title=Sustained-release potassium chloride overdose |journal=J. Toxicol. Clin. Toxicol. |volume=39 |issue=6 |pages=641–8 |year=2001 |pmid=11762675}}</ref> |
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Rare causes of hyperkalemia are discussed as follows. Acute digitalis overdose such as [[digoxin]] toxicity may cause hyperkalemia<ref>{{EMedicine|article|154336|Digitalis Toxicity}}</ref> through the inhibition of sodium-potassium-ATPase pump.<ref name="UpToDate causes and evaluation" /> Massive [[blood transfusion]] can cause hyperkalemia in infants due to leakage of potassium out of the red blood cells during storage.<ref name="UpToDate causes and evaluation" /> Giving [[Suxamethonium chloride|succinylcholine]] to people with conditions such as burns, trauma, infection, prolonged immobilisation can cause hyperkalemia due to widespread activation of acetylcholine receptors rather than a specific group of muscles. [[Arginine]] hydrochloride is used to treat [[refractory]] metabolic alkalosis. The arginine ions can enter cells and displace potassium out of the cells, causing hyperkalemia. Calcineurin inhibitors such as [[Ciclosporin|cyclosporine]], [[tacrolimus]], [[diazoxide]], and [[minoxidil]] can cause hyperkalemia.<ref name="UpToDate causes and evaluation" /> [[Box jellyfish]] venom can also cause hyperkalemia.<ref>{{Cite book |last=Haddad |first=Vidal |url=https://books.google.com/books?id=mR0DDQAAQBAJ&pg=PA11 |title=Medical Emergencies Caused by Aquatic Animals: A Zoological and Clinical Guide |date=2016 |publisher=Springer |isbn=9783319202884 |page=11}}</ref> |
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===Lethal injection=== |
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Hyperkalemia is intentionally brought about in an [[capital punishment|execution]] by [[lethal injection]], with [[potassium chloride]] being the third and last of the three drugs administered to cause death. |
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===Excessive intake=== |
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Excessive intake of potassium is not a primary cause of hyperkalemia because the human body usually can adapt to the rise in the potassium levels by increasing the excretion of potassium into urine through [[aldosterone]] hormone secretion and increasing the number of potassium secreting channels in kidney tubules.<ref name="UpToDate causes and evaluation" /> Acute hyperkalemia in infants is also rare even though their body volume is small, with accidental ingestion of potassium salts or potassium medications. Hyperkalemia usually develops when there are other co-morbidities such as [[hypoaldosteronism]] and [[chronic kidney disease]].<ref name="UpToDate causes and evaluation">{{Cite web |last=B Mount |first=David |last2=H Sterns |first2=Richard |last3=P Forman |first3=John |date=5 June 2017 |title=Causes and evaluation of hyperkalemia in adults |url=https://www.uptodate.com/contents/causes-and-evaluation-of-hyperkalemia-in-adults?source=search_result&search=hyperkalemia&selectedTitle=2~150 |url-access=subscription |access-date=28 September 2017 |publisher=[[UpToDate]]}}</ref> |
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===Pseudohyperkalemia=== |
===Pseudohyperkalemia=== |
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Pseudohyperkalemia occurs when the measured potassium level is falsely elevated.<ref name="Smellie2007">{{Cite journal |last=Smellie |first=W Stuart A |date=31 March 2007 |title=Spurious hyperkalaemia |journal=BMJ |volume=334 |issue=7595 |pages=693–695 |doi=10.1136/bmj.39119.607986.47 |pmc=1839224 |pmid=17395950}}</ref> This condition is usually suspected when the patient is clinically well without any ECG changes. Mechanical trauma during blood drawing can cause potassium leakage out of the red blood cells due to [[haemolysis]] of the blood sample.<ref name=Smellie2007/> Repeated fist clenching during the blood draw can cause a transient rise in potassium levels.<ref>{{Citation |last=Simon |first=Leslie V. |title=Hyperkalemia |date=2024 |work=StatPearls |url=http://www.ncbi.nlm.nih.gov/books/NBK470284/ |access-date=2024-04-27 |place=Treasure Island (FL) |publisher=StatPearls Publishing |pmid=29261936 |last2=Hashmi |first2=Muhammad F. |last3=Farrell |first3=Mitchell W.}}</ref> Prolonged length of blood storage can also increase serum potassium levels. Hyperkalemia may become apparent when a person's platelet concentration is more than 500,000/microL in a clotted blood sample ([[serum (blood)|serum]] blood sample). Potassium leaks out of platelets after clotting has occurred. A high white cell count (greater than 120,000/microL) in people with [[chronic lymphocytic leukemia]] increases the fragility of red blood cells, thus causing pseudohyperkalemia during blood processing. This problem can be avoided by processing serum samples, because clot formation protects the cells from haemolysis during processing. A familial form of pseudohyperkalemia, a benign condition characterised by increased serum potassium in whole blood stored at cold temperatures, also exists. This is due to increased potassium permeability in red blood cells.<ref name="UpToDate causes and evaluation" /> |
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Pseudohyperkalemia is a rise in the amount of potassium that occurs due to excessive leakage of potassium from cells, during or after blood is drawn. It is a laboratory artifact rather than a biological abnormality and can be misleading to caregivers.<ref>{{cite journal |last=Sevastos |first=N |coauthors=Theodossiades, G; Efstathiou, S; Papatheodoridis, GV; Manesis, E; Archimandritis, AJ |title=Pseudohyperkalemia in serum: the phenomenon and its clinical magnitude |journal=J. Lab. Clin. Med. |volume=147 |issue=3 |pages=139–144 |year=2006 |month=March |pmid=16503244 |doi=10.1016/j.lab.2005.11.008 |url=}}</ref> Pseudohyperkalemia is typically caused by [[hemolysis]] during [[venipuncture]] (by either excessive vacuum of the blood draw or by a collection needle that is of too fine a gauge); excessive tournequet time or fist clenching during phlebotomy (which presumably leads to efflux of potassium from the muscle cells into the bloodstream);<ref>{{cite journal |last=Don |first=BR |coauthors=Sebastian, A; Cheitlin, M; Christiansen, M; Schambelan, M |title=Pseudohyperkalemia caused by fist clenching during phlebotomy |journal=N. Engl. J. Med. |volume=322 |issue=18 |pages=1290–1292 |year=1990 |month=May |pmid=2325722 |doi= |url=}}</ref> or by a delay in the processing of the blood specimen. It can also occur in specimens from patients with abnormally high numbers of [[platelet]]s (>1,000,000/mm³), [[leukocyte]]s (> 100 000/mm³), or [[erythrocyte]]s (hematocrit > 55%). People with "leakier" [[cell membrane]]s have been found, whose blood must be separated immediately to avoid pseudohyperkalemia.<ref>{{cite journal |last=Iolascon |first=A |coauthors=Stewart, GW; Ajetunmobi, JF; ''et al.'' |title=Familial pseudohyperkalemia maps to the same locus as dehydrated hereditary stomatocytosis (hereditary xerocytosis) |journal=Blood |volume=93 |issue=9 |pages=3120–3123 |year=1999 |month=May |pmid=10216110 |doi= |url=http://www.bloodjournal.org/cgi/pmidlookup?view=long&pmid=10216110}}</ref> |
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==Mechanism== |
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Potassium is the most abundant [[intracellular]] [[cation]]. It is critically important for many physiologic processes, including maintenance of cellular [[membrane potential]], [[homeostasis]] of cell volume, and transmission of [[action potential]]s in [[nerve cell]]s. Its main dietary sources are [[vegetable]]s ([[tomato]] and [[potato]]), fruits ([[orange (fruit)|orange]] and [[banana]]) and [[meat]]. Elimination is through the [[gastrointestinal tract]] and the [[kidney]]. |
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=== Physiology === |
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The renal elimination of potassium is passive (through the [[glomeruli]]), and resorption is active in the [[proximal tubule]] and the ascending limb of the [[loop of Henle]]. There is active excretion of potassium in the [[distal tubule]] and the [[collecting duct]]; both are controlled by [[aldosterone]]. |
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Potassium is the most abundant [[intracellular]] [[cation]] and about 98% of the body's potassium is found inside cells, with the remainder in the [[extracellular fluid]] including the blood. Membrane potential is maintained principally by the [[Molecular diffusion|concentration gradient]] and membrane permeability to potassium with some contribution from the [[Na+/K+-ATPase|Na+/K+ pump]]. The potassium gradient is critically important for many physiological processes, including maintenance of cellular [[membrane potential]], [[homeostasis]] of cell volume, and transmission of [[action potential]]s in [[nerve cell]]s.<ref name="Kovesdy2015" /> |
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Potassium is eliminated from the body through the [[gastrointestinal tract]], [[kidney]] and [[sweat gland]]s. In the kidneys, elimination of potassium is passive (through the [[Glomerulus (kidney)|glomeruli]]), and reabsorption is active in the [[proximal tubule]] and the ascending limb of the [[loop of Henle]]. There is active excretion of potassium in the [[Distal convoluted tubule|distal tubule]] and the [[Collecting duct system|collecting duct]]; both are controlled by [[aldosterone]]. In sweat glands potassium elimination is quite similar to the kidney; its excretion is also controlled by aldosterone.{{medical citation needed|date=January 2014}} |
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Hyperkalemia develops when there is excessive production (oral intake, tissue breakdown) or ineffective elimination of potassium. Ineffective elimination can be hormonal (in [[aldosterone]] deficiency) or due to causes in the renal parenchyma that impair excretion. |
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Regulation of serum potassium is a function of intake, appropriate distribution between intracellular and extracellular compartments, and effective bodily excretion. In healthy individuals, homeostasis is maintained when cellular uptake and kidney excretion naturally counterbalance a patient's dietary intake of potassium.<ref>{{Cite journal |last=Brown |first=Robert |date=5 November 1984 |title=Potassium Homeostasis and clinical implications |journal=The American Journal of Medicine |volume=77 |issue=5 |pages=3–10 |doi=10.1016/s0002-9343(84)80002-9 |pmid=6388326}}</ref><ref name="isbn_9780323058766">{{Cite book |last=Weiner |first=ID |title=Comprehensive Clinical Nephrology |last2=Linas |first2=SL |last3=Wingo |first3=CS |date=2010 |publisher=Elsevier |isbn=9780323058766 |editor-last=Fluege |editor-first=J |edition=4th |pages=118–129 |chapter=Chapter 9 Disorder of Potassium Metabolism |editor-last2=Johnson |editor-first2=R |editor-last3=Feehally |editor-first3=J}}</ref> When kidney function becomes compromised, the ability of the body to effectively regulate serum potassium via the kidney declines. To compensate for this deficit in function, the colon increases its potassium secretion as part of an adaptive response. However, serum potassium remains elevated as the colonic compensating mechanism reaches its limits.<ref>{{Cite journal |last=Mathialahan |first=T |last2=Maclennan |first2=KA |last3=Sandle |first3=LN |last4=Verbeke |first4=C |last5=Sandle |first5=GI |date=2005 |title=Enhanced large intestinal potassium permeability in end-stage renal disease |journal=Journal of Pathology |volume=206 |issue=1 |pages=46–51 |doi=10.1002/path.1750 |pmid=15772943 |s2cid=9679428}}</ref><ref>{{Cite journal |last=Evans |first=KJ |last2=Greenberg |first2=A |date=2005 |title=Hyperkalemia: A review |journal=J Intensive Care Med |volume=20 |issue=5 |pages=272–290 |doi=10.1177/0885066605278969 |pmid=16145218 |s2cid=42985122}}</ref> |
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Increased extracellular potassium levels result in [[depolarization]] of the membrane potentials of cells. This depolarization opens some [[sodium channel|voltage-gated sodium channel]]s, but not enough to generate an action potential. After a short while, the open sodium channels inactivate and become [[refractory period (physiology)|refractory]], increasing the threshold to generate an action potential. This leads to the impairment of neuromuscular, [[cardiac]], and [[gastrointestinal]] organ systems. Of most concern is the impairment of cardiac conduction which can result in [[ventricular fibrillation]] or [[asystole]]. |
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=== Elevated potassium === |
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During extreme exercise, potassium is released from active muscle and the serum potassium rises to a point that would be dangerous at rest. For unclear reasons, it appears as if the high levels of adrenaline and noradrenaline have a protective effect on the cardiac electrophysiology.<ref>{{cite journal |last=Lindinger |first=MI |title=Potassium regulation during exercise and recovery in humans: implications for skeletal and cardiac muscle |journal=J. Mol. Cell. Cardiol. |volume=27 |issue=4 |pages=1011–1022 |year=1995 |month=April |pmid=7563098 |doi= 10.1016/0022-2828(95)90070-5|url=http://linkinghub.elsevier.com/retrieve/pii/0022-2828(95)90070-5}}</ref> |
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Hyperkalemia develops when there is excess production (oral intake, tissue breakdown) or ineffective elimination of potassium. Ineffective elimination can be hormonal (in aldosterone deficiency) or due to causes in the kidney that impair excretion.<ref>{{Cite journal |last=Desai |first=Akshay |date=14 October 2008 |title=Hyperkalemia Associated With Inhibitors of the Renin-Angiotensin-Aldosterone System: Balancing Risk and Benefit |journal=Circulation |volume=118 |issue=16 |pages=1609–1611 |doi=10.1161/CIRCULATIONAHA.108.807917 |pmid=18852376 |doi-access=free}}</ref> |
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Increased extracellular potassium levels result in [[depolarization]] of the membrane potentials of cells due to the increase in the [[Reversal potential|equilibrium potential]] of potassium. This depolarization opens some voltage-gated [[sodium channel]]s, but also increases the inactivation at the same time. Since depolarization due to concentration change is slow, it never generates an action potential by itself; instead, it results in [[neural accommodation|accommodation]]. Above a certain level of potassium the depolarization inactivates sodium channels, opens potassium channels, thus the cells become [[refractory period (physiology)|refractory]]. This leads to the impairment of neuromuscular, [[cardiac]], and [[gastrointestinal]] organ systems. Of most concern is the impairment of cardiac conduction, which can cause [[ventricular fibrillation]] and/or [[Bradycardia|abnormally slow heart rhythms]].<ref name="Kovesdy2015" /> |
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Patients with the rare hereditary condition of [[hyperkalemic periodic paralysis]] appear to have a heightened sensitivity of muscular symptoms that are associated with transient elevation of potassium levels. Episodes of muscle weakness and spasms can be precipitated by exercise or fasting in these subjects. |
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==Diagnosis== |
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[[File:HyperK2014.JPG|thumb|upright=1.5|An ECG of a person with a potassium of 5.7 showing large T waves and small P waves]] |
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With mild to moderate hyperkalemia, there is reduction of the size of the [[P wave (electrocardiography)|P wave]] and development of peaked [[T wave]]s. Severe hyperkalemia results in a widening of the [[QRS complex]], and the [[EKG]] complex can evolve to a [[sinusoidal]] shape. There appears to be a direct effect of elevated potassium on some of the potassium channels that increases their activity and speeds membrane repolarization. Also, (as noted [[#Pathophysiology|above]]), hyperkalemia causes an overall membrane depolarization that inactivates many sodium channels. The faster repolarization of the cardiac [[action potential]] causes the tenting of the T waves, and the inactivation of sodium channels causes a sluggish conduction of the electrical wave around the heart, which leads to smaller P waves and widening of the QRS complex. |
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To gather enough information for diagnosis, the measurement of potassium must be repeated, as the elevation can be due to [[hemolysis]] in the first sample. The normal serum level of potassium is 3.5 to 5{{nbsp}}mmol/L. Generally, blood tests for [[kidney function]] ([[creatinine]], [[blood urea nitrogen]]), [[glucose]] and occasionally [[creatine kinase]] and [[cortisol]] are performed. Calculating the [[trans-tubular potassium gradient]] can sometimes help in distinguishing the cause of the hyperkalemia.{{medical citation needed|date=January 2014}} |
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Also, [[electrocardiography]] (ECG) may be performed to determine if there is a significant risk of abnormal heart rhythms.<ref name="Kovesdy2015" /> Physicians taking a [[medical history]] may focus on [[Nephrology|kidney disease]] and [[medication]] use (e.g. [[potassium-sparing diuretic]]s), both of which are known causes of hyperkalemia.<ref name="Kovesdy2015" /> |
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=== Definitions === |
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Normal serum potassium levels are generally considered to be between 3.5 and 5.3 [[Molar concentration|mmol/L]].<ref name=EU2010/> Levels above 5.5{{nbsp}}mmol/L generally indicate hyperkalemia, and those below 3.5{{nbsp}}mmol/L indicate [[hypokalemia]].<ref name=Leh2011/><ref name=EU2010/> |
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===ECG findings=== |
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With mild to moderate hyperkalemia, there is prolongation of the PR interval and development of peaked [[T wave]]s.<ref name="Kovesdy2015" /> Severe hyperkalemia results in a widening of the [[QRS complex]], and the [[Electrocardiography|ECG]] complex can evolve to a [[Sine wave|sinusoidal]] shape.<ref>{{Cite web |title=Hyperkalaemia - ECG Features - Management |url=http://teachmesurgery.com/post-operative/endocrine/hyperkalaemia/ |url-status=live |archive-url=https://web.archive.org/web/20160325151835/http://teachmesurgery.com/post-operative/endocrine/hyperkalaemia/ |archive-date=2016-03-25 |access-date=2016-03-25}}</ref> There appears to be a direct effect of elevated potassium on some of the potassium channels that increases their activity and speeds membrane repolarisation. Also, (as noted [[#Physiology|above]]), hyperkalemia causes an overall membrane depolarization that inactivates many sodium channels. The faster repolarisation of the cardiac [[action potential]] causes the tenting of the T waves, and the inactivation of sodium channels causes a sluggish conduction of the electrical wave around the heart, which leads to smaller P waves and widening of the QRS complex.{{medical citation needed|date=January 2014}} Some of potassium currents are sensitive to extracellular potassium levels, for reasons that are not well understood. As the extracellular potassium levels increase, potassium conductance is increased so that more potassium leaves the myocyte in any given time period.<ref>{{Cite journal |vauthors=Parham WA, Mehdirad AA, Biermann KM, Fredman CS |year=2006 |title=Hyperkalemia Revisited |journal=Tex. Heart Inst. J. |volume=33 |issue=1 |pages=40–47 |pmc=1413606 |pmid=16572868}}</ref> To summarize, classic ECG changes associated with hyperkalemia are seen in the following progression: peaked T wave, shortened QT interval, lengthened PR interval, increased QRS duration, and eventually absence of the P wave with the QRS complex becoming a sine wave. Bradycardia, junctional rhythms and QRS widening are particularly associated with increased risk of adverse outcomes<ref>{{Cite journal |last=Clase |first=Catherine M. |last2=Carrero |first2=Juan-Jesus |last3=Ellison |first3=David H. |last4=Grams |first4=Morgan E. |last5=Hemmelgarn |first5=Brenda R. |last6=Jardine |first6=Meg J. |last7=Kovesdy |first7=Csaba P. |last8=Kline |first8=Gregory A. |last9=Lindner |first9=Gregor |last10=Obrador |first10=Gregorio T. |last11=Palmer |first11=Biff F. |last12=Cheung |first12=Michael |last13=Wheeler |first13=David C. |last14=Winkelmayer |first14=Wolfgang C. |last15=Pecoits-Filho |first15=Roberto |date=January 2020 |title=Potassium homeostasis and management of dyskalemia in kidney diseases: conclusions from a Kidney Disease: Improving Global Outcomes (KDIGO) Controversies Conference |journal=Kidney International |volume=97 |issue=1 |pages=42–61 |doi=10.1016/j.kint.2019.09.018 |pmid=31706619 |doi-access=free |hdl-access=free |last16=Ashuntantang |first16=Gloria E. |last17=Bakker |first17=Stephan J.L. |last18=Bakris |first18=George L. |last19=Bhandari |first19=Sunil |last20=Burdmann |first20=Emmanuel A. |last21=Campbell |first21=Katrina L. |last22=Charytan |first22=David M. |last23=Clegg |first23=Deborah J. |last24=Cuppari |first24=Lilian |last25=Goldsmith |first25=David |last26=Hallan |first26=Stein I. |last27=He |first27=Jiang |last28=Herzog |first28=Charles A. |last29=Hoenig |first29=Melanie P. |last30=Hoorn |first30=Ewout J. |last31=Leipziger |first31=Jens Georg |last32=Leonberg-Yoo |first32=Amanda K. |last33=Lerma |first33=Edgar V. |last34=Lopez-Almaraz |first34=Jose Ernesto |last35=Małyszko |first35=Jolanta |last36=Mann |first36=Johannes F.E. |last37=Marklund |first37=Matti |last38=McDonough |first38=Alicia A. |last39=Nagahama |first39=Masahiko |last40=Navaneethan |first40=Sankar D. |last41=Pitt |first41=Bertram |last42=Pochynyuk |first42=Oleh M. |last43=Proença de Moraes |first43=Thyago |last44=Rafique |first44=Zubaid |last45=Robinson |first45=Bruce M. |last46=Roger |first46=Simon D. |last47=Rossignol |first47=Patrick |last48=Singer |first48=Adam J. |last49=Smyth |first49=Andrew |last50=Sood |first50=Manish M. |last51=Walsh |first51=Michael |last52=Weir |first52=Matthew R. |last53=Wingo |first53=Charles S. |hdl=10072/392924}}</ref> |
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The serum potassium concentration at which electrocardiographic changes develop is somewhat variable. Although the factors influencing the effect of serum potassium levels on cardiac electrophysiology are not entirely understood, the concentrations of other [[electrolyte]]s, as well as levels of catecholamines, play a major role.{{medical citation needed|date=January 2014}} |
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ECG findings are not a reliable finding in hyperkalemia. In a retrospective review, blinded cardiologists documented peaked T-waves in only 3 of 90 ECGs with hyperkalemia. [[Sensitivity and specificity|Sensitivity]] of peaked-Ts for hyperkalemia ranged from 0.18 to 0.52 depending on the criteria for peak-T waves.{{medical citation needed|date=January 2014}} |
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==Prevention== |
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Preventing recurrence of hyperkalemia typically involves reduction of dietary potassium, removal of an offending medication, and/or the addition of a [[diuretic]] (such as [[furosemide]] or [[hydrochlorothiazide]]).<ref name="Kovesdy2015" /> Sodium [[polystyrene sulfonate]] and [[sorbitol]] (combined as Kayexalate) are occasionally used on an ongoing basis to maintain lower serum levels of potassium though the safety of long-term use of sodium polystyrene sulfonate for this purpose is not well understood.<ref name="Kovesdy2015" /> |
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High dietary sources include [[vegetable]]s such as [[avocado]]s,<ref>{{Cite journal |vauthors=Dreher ML, Davenport AJ |year=2013 |title=Hass avocado composition and potential health effects |journal=Crit Rev Food Sci Nutr |volume=53 |issue=7 |pages=738–50 |doi=10.1080/10408398.2011.556759 |pmc=3664913 |pmid=23638933}}</ref><ref>[http://www.upi.com/Avocado-has-more-potassium-than-banana/60161304653187 Avocado has more potassium than banana] {{webarchive|url=https://web.archive.org/web/20170203080008/http://www.upi.com/Avocado-has-more-potassium-than-banana/60161304653187 |date=2017-02-03 }} 5 May 2011, [[UPI]].com</ref> [[tomato]]es and [[potato]]es, fruits such as [[banana]]s, [[orange (fruit)|orange]]s and nuts.<ref>{{Cite web |title=Potassium And Your CKD Diet |url=https://www.kidney.org/atoz/content/potassium |url-status=live |archive-url=https://web.archive.org/web/20151222105958/https://www.kidney.org/atoz/content/potassium |archive-date=22 December 2015 |access-date=21 December 2015 |publisher=National Kidney Foundation (NKF)}}</ref> |
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The serum K<sup>+</sup> concentration at which electrocardiographic changes develop is somewhat variable.<ref>Wrenn KD, Slovis CM, Slovis BS. The ability of physicians to predict hyperkalemia from the ECG. Ann Emerg Med 20: 1229-1232, 1991. PMID 1952310</ref><ref>Aslam S, Friedman EA, Ifudu O. Electrocardiography is unreliable in detecting potentially lethal hyperkalaemia in haemodialysis patients. Nephrol Dial Transplant 17: 1639-1642, 2002. PMID 12198216</ref> Although the factors influencing the effect of serum potassium levels on cardiac electrophysiology are not entirely understood, the concentrations of other electrolytes, as well as levels of catecholamines, play a major role.<ref>Surawicz B. Electrolytes and the Electrocardiogram. Am J Cardiol 12: 656-662, 1963. PMID 5338052</ref><ref>Leitch SP, Patterson DJ. Interactive effects of K+, acidosis, and catecholamines on isolated rabbit heart: implications for exercise. J Appl Physiol 77: 1164-1171, 1994. PMID 7836118</ref> |
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==Treatment== |
==Treatment== |
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Emergency lowering of potassium levels is needed when new arrhythmias occur at any level of potassium in the blood, or when potassium levels exceed 6.5{{nbsp}}mmol/L. Several agents are used to temporarily lower K<sup>+</sup> levels. The choice depends on the degree and cause of the hyperkalemia, and other aspects of the person's condition. |
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===Myocardial excitability=== |
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'''Acute''': |
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Calcium ([[calcium chloride]] or [[calcium gluconate]]) increases [[threshold potential]] through a mechanism that is still unclear, thus restoring normal gradient between threshold potential and resting membrane potential, which is elevated abnormally in hyperkalemia. A standard ampule of 10% calcium chloride is 10 mL and contains 6.8{{nbsp}}mmol of calcium. A standard ampule of 10% calcium gluconate is also 10 mL but has only 2.26{{nbsp}}mmol of calcium. Clinical practice guidelines recommend giving 6.8{{nbsp}}mmol for typical EKG findings of hyperkalemia.<ref name="Kovesdy2015" /> This is 10 mL of 10% calcium chloride or 30 mL of 10% calcium gluconate.<ref name="Kovesdy2015" /> Though calcium chloride is more concentrated, it is caustic to the veins and should only be given through a central line.<ref name="Kovesdy2015" /> Onset of action is less than one to three minutes and lasts about 30–60 minutes.<ref name="Kovesdy2015" /> The goal of treatment is to normalise the EKG and doses can be repeated if the EKG does not improve within a few minutes.<ref name="Kovesdy2015" /> |
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When arrhythmias occur, or when potassium levels exceed 6.5 mmol/l, emergency lowering of potassium levels is mandated. Several agents are used to lower K levels. Choice depends on the degree and cause of the hyperkalemia, and other aspects of the patient's condition. |
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* [[Calcium]] supplementation (calcium gluconate 10% (10ml), preferably through a [[central venous catheter]] as the calcium may cause [[phlebitis]]) does not lower potassium but decreases [[myocardium|myocardial]] excitability, protecting against life threatening [[arrhythmias]]. |
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* [[Insulin]] (e.g. intravenous injection of 10-15u of regular insulin {along with 50ml of 50% dextrose to prevent hypoglycemia}) will lead to a shift of potassium ions into cells, secondary to increased activity of the [[sodium-potassium ATPase]]. |
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* [[Bicarbonate]] therapy (e.g. 1 ampule (45mEq) infused over 5 minutes) is effective in cases of metabolic acidosis. The bicarbonate ion will stimulate an exchange of cellular H<sup>+</sup> for Na<sup>+</sup>, thus leading to stimulation of the [[sodium-potassium ATPase]]. |
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* [[Salbutamol]] (albuterol, Ventolin) is a β<sub>2</sub>-selective catecholamine that is administered by nebulizer (e.g. 10–20 mg). This drug promotes movement of K into cells, lowering the blood levels. |
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* Refractory or severe cases may need [[dialysis]] to remove the potassium from the circulation. |
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Some textbooks suggest that calcium should not be given in digoxin toxicity as it has been linked to cardiovascular collapse in humans and increased digoxin toxicity in animal models. Recent literature questions the validity of this concern.{{medical citation needed|date=January 2014}} |
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'''Prevention''': |
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* Preventing recurrence of hyperkalemia typically involves reduction of dietary potassium, removal of an offending medication, and/or the addition of a [[diuretic]] (such as [[furosemide]] (Lasix) or [[hydrochlorothiazide]]). |
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* [[Polystyrene sulfonate]] (Calcium Resonium, Kayexalate) is a binding resin that binds K within the intestine and removes it from the body by defecation. Calcium Resonium (15g three times a day in water) can be given by mouth. Kayexelate (30g) can be given by mouth or as an [[enema]]. In both cases, the resin absorbs K within the intestine and carries it out of the body by [[defecation]]. This medication may cause diarrhea. |
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===Temporary measures=== |
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Several medical treatments shift potassium ions from the bloodstream into the cellular compartment, thereby reducing the risk of complications. The effect of these measures tends to be short-lived, but may temporise the problem until potassium can be removed from the body.<ref name="pmid20855477">{{Cite journal |vauthors=Elliott MJ, Ronksley PE, Clase CM, Ahmed SB, Hemmelgarn BR |date=October 2010 |title=Management of patients with acute hyperkalemia |journal=CMAJ |volume=182 |issue=15 |pages=1631–5 |doi=10.1503/cmaj.100461 |pmc=2952010 |pmid=20855477}}</ref> |
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* [[Hypokalemia]] |
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* [[Insulin]] (e.g. intravenous injection of 10 units of regular insulin along with 50 mL of 50% dextrose to prevent [[hypoglycemia|the blood sugar from dropping too low]]) leads to a shift of potassium ions into cells, secondary to increased activity of the [[Na+/K+-ATPase|sodium-potassium ATPase]].<ref name="AHA2010">{{Cite journal |vauthors=Vanden Hoek TL, Morrison LJ, Shuster M, Donnino M, Sinz E, Lavonas EJ, Jeejeebhoy FM, Gabrielli A |date=2010-11-02 |title=Part 12: cardiac arrest in special situations: 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care |journal=Circulation |volume=122 |issue=18 Suppl 3 |pages=S829–61 |doi=10.1161/CIRCULATIONAHA.110.971069 |pmid=20956228 |doi-access=free}}</ref> Its effects last a few hours, so it sometimes must be repeated while other measures are taken to suppress potassium levels more permanently. The insulin is usually given with an appropriate amount of glucose to help prevent hypoglycemia following the insulin administration, though hypoglycaemia remains common especially in the context of acute or chronic renal impairment<ref>{{Cite journal |last=Schafers |first=Stephen |last2=Naunheim |first2=Rosanne |last3=Vijayan |first3=Anitha |last4=Tobin |first4=Garry |date=March 2012 |title=Incidence of hypoglycemia following insulin-based acute stabilization of hyperkalemia treatment |journal=Journal of Hospital Medicine |volume=7 |issue=3 |pages=239–242 |doi=10.1002/jhm.977 |pmid=22489323 |doi-access=free}}</ref> and capillary blood glucose measurements should be taken regularly after administration to identify this. |
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* [[Renal failure]] |
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* [[Salbutamol]] (albuterol), a β<sub>2</sub>-selective catecholamine, is administered by nebuliser (e.g. 10–20{{nbsp}}mg). This medication also lowers blood levels of K<sup>+</sup> by promoting its movement into cells, and will work within 30 minutes.<ref name=AHA2010/> It is recommended to use 20 mg for maximum potassium lowering effect, but to use lower doses if the patient is tachycardic or has ischaemic heart disease. Note that 12-40% of patients do not respond to salbutamol therapy for reasons unknown, especially if on beta-blockers, so it should not be used as monotherapy<ref>{{Cite journal |last=Ahee |first=Peter |last2=Crowe |first2=Alexander V. |date=1 May 2000 |title=The management of hyperkalaemia in the emergency department |journal=Emergency Medicine Journal |volume=17 |issue=3 |pages=188–191 |doi=10.1136/emj.17.3.188 |pmc=1725366 |pmid=10819381 |doi-access=free}}</ref> |
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* [[Sodium bicarbonate]] may be used with the above measures if it is believed the person has [[metabolic acidosis]],<ref name=EU2010/> though time to effectiveness is longer and its use is controversial. |
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===Elimination=== |
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Severe cases require [[hemodialysis]], which are the most rapid methods of removing potassium from the body.<ref name=AHA2010/> These are typically used if the underlying cause cannot be corrected swiftly while temporising measures are instituted or there is no response to these measures. |
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[[Loop diuretics]] ([[furosemide]], [[bumetanide]], [[torasemide]]) and [[thiazide]] diuretics (e.g., [[chlortalidone]], [[hydrochlorothiazide]], or [[chlorothiazide]]) can increase kidney potassium excretion in people with intact kidney function.<ref name=AHA2010/> |
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Potassium can bind to a number of agents in the gastrointestinal tract.<ref>{{Cite journal |last=Hollander-Rodriguez |first=Joyce C. |last2=Calvert |first2=James F. |date=15 January 2006 |title=Hyperkalemia |url=https://www.aafp.org/link_out?pmid=16445274 |journal=American Family Physician |volume=73 |issue=2 |pages=283–290 |pmid=16445274}}</ref><ref name="isbn_9780323058766" /> Sodium [[polystyrene sulfonate]] with [[sorbitol]] (Kayexalate) has been approved for this use and can be given by mouth or rectally.<ref name=AHA2010/> However, high quality evidence to demonstrate the effectiveness of sodium polystyrene are lacking, and use of sodium polystyrene sulfonate, particularly with high sorbitol content, is uncommonly but convincingly [[Correlation and dependence|associated]] with [[Large intestine|colonic]] [[necrosis]].<ref name="Kamel2012">{{Cite journal |vauthors=Kamel KS, Schreiber M |year=2012 |title=Asking the question again: Are cation exchange resins effective for the treatment of hyperkalemia? |journal=Nephrology Dialysis Transplantation |volume=27 |issue=12 |pages=4294–7 |doi=10.1093/ndt/gfs293 |pmid=22989741 |doi-access=free}}</ref><ref name="Watson2010">{{Cite journal |vauthors=Watson M, Abbott KC, Yuan CM |year=2010 |title=Damned if You Do, Damned if You Don't: Potassium Binding Resins in Hyperkalemia |journal=Clinical Journal of the American Society of Nephrology |volume=5 |issue=10 |pages=1723–6 |doi=10.2215/CJN.03700410 |pmid=20798253 |doi-access=free}}</ref><ref name="Sterns2010">{{Cite journal |vauthors=Sterns RH, Rojas M, Bernstein P, Chennupati S |date=May 2010 |title=Ion-exchange resins for the treatment of hyperkalemia: are they safe and effective? |journal=J. Am. Soc. Nephrol. |volume=21 |issue=5 |pages=733–5 |doi=10.1681/ASN.2010010079 |pmid=20167700 |doi-access=free}}</ref> There are no systematic studies (>6 months) looking at the long-term safety of this medication.<ref>{{Cite journal |last=Harel |first=Ziv |last2=Harel |first2=Shai |last3=Shah |first3=Prakesh S. |last4=Wald |first4=Ron |last5=Perl |first5=Jeffrey |last6=Bell |first6=Chaim M. |date=March 2013 |title=Gastrointestinal Adverse Events with Sodium Polystyrene Sulfonate (Kayexalate) Use: A Systematic Review |journal=The American Journal of Medicine |volume=126 |issue=3 |pages=264.e9–264.e24 |doi=10.1016/j.amjmed.2012.08.016 |pmid=23321430}}</ref> |
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[[Patiromer]] is taken by mouth and works by binding free [[potassium]] ions in the [[gastrointestinal tract]] and releasing [[calcium]] ions for exchange, thus lowering the amount of potassium available for absorption into the bloodstream and increasing the amount lost via the feces.<ref name="Kovesdy2015" /><ref>{{Cite press release |title=FDA approves new drug to treat hyperkalemia |date=22 October 2015 |url=https://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm468546.htm |access-date=1 November 2015 |url-status=dead |archive-url=https://web.archive.org/web/20151107235654/https://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm468546.htm |archive-date=7 November 2015 |website=[[Food and Drug Administration]] (FDA)}}</ref> The net effect is a reduction of potassium levels in the blood serum.<ref name="Kovesdy2015" /> |
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[[Sodium zirconium cyclosilicate]] is a medication that binds [[potassium]] in the [[gastrointestinal tract]] in exchange for sodium and hydrogen ions.<ref name="Kovesdy2015" /> Onset of effects occurs in one to six hours.<ref name=AHFS2019Zir/> It is taken by mouth.<ref name="AHFS2019Zir">{{Cite web |title=Sodium Zirconium Cyclosilicate Monograph for Professionals |url=https://www.drugs.com/monograph/sodium-zirconium-cyclosilicate.html |access-date=11 October 2019 |website=Drugs.com |language=en}}</ref> |
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==Epidemiology== |
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Hyperkalemia is rare among those who are otherwise healthy.<ref name=Kov2016/> Among those who are in hospital, rates are between 1% and 2.5%.<ref name=BMJ2015/> |
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==Society and culture== |
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In the United States, hyperkalemia is induced by [[lethal injection]] in [[capital punishment]] cases. [[Potassium chloride]] is the last of the three drugs administered and actually causes death. Injecting potassium chloride into the heart muscle disrupts the signal that causes the heart to beat. This same amount of potassium chloride would do no harm if taken orally and not injected directly into the blood.{{cn|date=November 2024}} |
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==References== |
==References== |
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== External links == |
== External links == |
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{{Medical resources |
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* [http://www.nal.usda.gov/fnic/foodcomp/Data/SR20/nutrlist/sr20w306.pdf Content of Selected Foods per Common Measure, sorted by nutrient content (Potassium)] |
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| DiseasesDB = 6242 |
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:USDA National Nutrient Database for Standard Reference, Release 20] |
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| ICD10 = {{ICD10|E|87|5|e|70}} |
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* [http://www.umassmed.edu/uploadedFiles/SourcesDietaryPotassium.pdf List of foods rich in potassium] |
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| ICD9 = {{ICD9|276.7}} |
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* [http://www.kidney.org/ATOZ/atozItem.cfm?id=103 National Kidney Foundation site on potassium content of foods] |
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| MedlinePlus = 001179 |
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* [https://fdc.nal.usda.gov/fdc-app.html#/?component=0 USDA National Nutrient Database for Standard Reference, Release 26] {{Webarchive|url=https://web.archive.org/web/20140301101828/http://ndb.nal.usda.gov/ndb/nutrients/index |date=1 March 2014 }} |
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* [https://web.archive.org/web/20170103150926/http://www.umassmed.edu/uploadedFiles/SourcesDietaryPotassium.pdf List of foods rich in potassium] |
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* [http://www.kidney.org/atoz/content/potassium.cfm National Kidney Foundation site on potassium content of foods] {{Webarchive|url=https://web.archive.org/web/20140708145657/http://www.kidney.org/atoz/content/potassium.cfm |date=8 July 2014 }} |
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{{Electrolyte abnormalities}} |
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{{Fluid, electrolyte, acid base metabolic pathology}} |
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[[Category:Electrolyte disturbances]] |
[[Category:Electrolyte disturbances]] |
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[[Category:Endocrinology]] |
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[[Category:Medical emergencies]] |
[[Category:Medical emergencies]] |
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[[Category:Nephrology]] |
[[Category:Nephrology]] |
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[[Category:Potassium]] |
[[Category:Potassium]] |
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[[Category:Wikipedia medicine articles ready to translate]] |
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[[Category:Wikipedia neurology articles ready to translate]] |
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[[ar:فرط بوتاسيوم الدم]] |
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[[bs:Hiperkalemija]] |
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[[de:Hyperkaliämie]] |
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[[et:Hüperkaleemia]] |
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[[es:Hipercalemia]] |
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[[fr:Hyperkaliémie]] |
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[[gl:Hiperpotasemia]] |
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[[hr:Hiperkalijemija]] |
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[[it:Iperkaliemia]] |
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[[he:היפרקלמיה]] |
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[[ja:高カリウム血症]] |
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Latest revision as of 15:03, 21 November 2024
Hyperkalemia | |
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Other names | Hyperkalaemia |
Electrocardiography showing precordial leads in hyperkalemia. | |
Pronunciation | |
Specialty | Critical care medicine, nephrology |
Symptoms | Palpitations, muscle pain, muscle weakness, numbness[1][2] |
Complications | Cardiac arrest[1][3] |
Causes | Kidney failure, hypoaldosteronism, rhabdomyolysis, certain medications[1] |
Diagnostic method | Blood potassium > 5.5 mmol/L, electrocardiogram[3][4] |
Differential diagnosis | Pseudohyperkalemia[1][2] |
Treatment | Medications, low potassium diet, hemodialysis[1] |
Medication | Calcium gluconate, dextrose with insulin, salbutamol, sodium bicarbonate[1][3][5] |
Frequency | ~2% (people in hospital)[2] |
Hyperkalemia is an elevated level of potassium (K+) in the blood.[1] Normal potassium levels are between 3.5 and 5.0 mmol/L (3.5 and 5.0 mEq/L) with levels above 5.5 mmol/L defined as hyperkalemia.[3][4] Typically hyperkalemia does not cause symptoms.[1] Occasionally when severe it can cause palpitations, muscle pain, muscle weakness, or numbness.[1][2] Hyperkalemia can cause an abnormal heart rhythm which can result in cardiac arrest and death.[1][3]
Common causes of hyperkalemia include kidney failure, hypoaldosteronism, and rhabdomyolysis.[1] A number of medications can also cause high blood potassium including spironolactone, NSAIDs, and angiotensin converting enzyme inhibitors.[1] The severity is divided into mild (5.5–5.9 mmol/L), moderate (6.0–6.4 mmol/L), and severe (>6.5 mmol/L).[3] High levels can be detected on an electrocardiogram (ECG).[3] Pseudohyperkalemia, due to breakdown of cells during or after taking the blood sample, should be ruled out.[1][2]
Initial treatment in those with ECG changes is salts, such as calcium gluconate or calcium chloride.[1][3] Other medications used to rapidly reduce blood potassium levels include insulin with dextrose, salbutamol, and sodium bicarbonate.[1][5] Medications that might worsen the condition should be stopped and a low potassium diet should be started.[1] Measures to remove potassium from the body include diuretics such as furosemide, potassium-binders such as polystyrene sulfonate (Kayexalate) and sodium zirconium cyclosilicate, and hemodialysis.[1] Hemodialysis is the most effective method.[3]
Hyperkalemia is rare among those who are otherwise healthy.[6] Among those who are hospitalized, rates are between 1% and 2.5%.[2] It is associated with an increased mortality, whether due to hyperkalaemia itself or as a marker of severe illness, especially in those without chronic kidney disease.[7][6] The word hyperkalemia comes from hyper- 'high' + kalium 'potassium' + -emia 'blood condition'.[8][9]
Signs and symptoms
[edit]The symptoms of an elevated potassium level are generally few and nonspecific.[10] Nonspecific symptoms may include feeling tired, numbness and weakness.[10] Occasionally palpitations and shortness of breath may occur.[10][11][12] Hyperventilation may indicate a compensatory response to metabolic acidosis, which is one of the possible causes of hyperkalemia.[13] Often, however, the problem is detected during screening blood tests for a medical disorder, or after hospitalization for complications such as cardiac arrhythmia or sudden cardiac death. High levels of potassium (> 5.5 mmol/L) have been associated with cardiovascular events.[13]
Causes
[edit]Ineffective elimination
[edit]Decreased kidney function is a major cause of hyperkalemia. This is especially pronounced in acute kidney injury where the glomerular filtration rate and tubular flow are markedly decreased, characterized by reduced urine output.[13] This can lead to a dramatically elevated potassium in conditions of increased cell breakdown as the potassium is released from the cells and cannot be eliminated in the kidney. In chronic kidney disease, hyperkalemia occurs as a result of reduced aldosterone responsiveness and reduced sodium and water delivery in distal tubules.[14]
Medications that interfere with urinary excretion by inhibiting the renin–angiotensin system is one of the most common causes of hyperkalemia. Examples of medications that can cause hyperkalemia include ACE inhibitors, angiotensin receptor blockers,[13] non-selective beta blockers, and calcineurin inhibitor immunosuppressants such as ciclosporin and tacrolimus.[15] For potassium-sparing diuretics, such as amiloride and triamterene; both the drugs block epithelial sodium channels in the collecting tubules, thereby preventing potassium excretion into urine.[14] Spironolactone acts by competitively inhibiting the action of aldosterone.[13] NSAIDs such as ibuprofen, naproxen, or celecoxib inhibit prostaglandin synthesis, leading to reduced production of renin and aldosterone, causing potassium retention.[16] The antibiotic trimethoprim and the antiparasitic medication pentamidine inhibits potassium excretion, which is similar to mechanism of action by amiloride and triamterene.[17]
Mineralocorticoid (aldosterone) deficiency or resistance can also cause hyperkalemia. Primary adrenal insufficiency are: Addison's disease[18] and congenital adrenal hyperplasia (CAH) (including enzyme deficiencies such as 21α hydroxylase, 17α hydroxylase, 11β hydroxylase, or 3β dehydrogenase).[19]
- Type IV renal tubular acidosis (aldosterone resistance of the kidney's tubules)
- Gordon's syndrome (pseudohypoaldosteronism type II) ("familial hypertension with hyperkalemia"), a rare genetic disorder caused by defective modulators of salt transporters, including the thiazide-sensitive Na-Cl cotransporter.
Excessive release from cells
[edit]Metabolic acidosis can cause hyperkalemia as the elevated hydrogen ions in the cells can displace potassium, causing the potassium ions to leave the cell and enter the bloodstream. However, in respiratory acidosis or organic acidosis such as lactic acidosis, the effect on serum potassium are much less significant although the mechanisms are not completely understood.[14]
Insulin deficiency can cause hyperkalemia as the hormone insulin increases the uptake of potassium into the cells. Hyperglycemia can also contribute to hyperkalemia by causing hyperosmolality in extracellular fluid, increasing water diffusion out of the cells and causes potassium to move alongside water out of the cells also. The co-existence of insulin deficiency, hyperglycemia, and hyperosmolality is often seen in those affected by diabetic ketoacidosis. Apart from diabetic ketoacidosis, there are other causes that reduce insulin levels such as the use of the medication octreotide, and fasting which can also cause hyperkalemia. Increased tissue breakdown such as rhabdomyolysis, burns, or any cause of rapid tissue necrosis, including tumor lysis syndrome can cause the release of intracellular potassium into blood, causing hyperkalemia.[13][14]
Beta2-adrenergic agonists act on beta-2 receptors to drive potassium into the cells. Therefore, beta blockers can raise potassium levels by blocking beta-2 receptors. However, the rise in potassium levels is not marked unless there are other co-morbidities present. Examples of drugs that can raise the serum potassium are non-selective beta-blockers such as propranolol and labetalol. Beta-1 selective blockers such as metoprolol do not increase serum potassium levels.[14][medical citation needed]
Exercise can cause a release of potassium into bloodstream by increasing the number of potassium channels in the cell membrane. The degree of potassium elevation varies with the degree of exercise, which range from 0.3 meq/L in light exercise to 2 meq/L in heavy exercise, with or without accompanying ECG changes or lactic acidosis. However, peak potassium levels can be reduced by prior physical conditioning and potassium levels are usually reversed several minutes after exercise.[14] High levels of adrenaline and noradrenaline have a protective effect on the cardiac electrophysiology because they bind to beta 2 adrenergic receptors, which, when activated, extracellularly decrease potassium concentration.[20]
Hyperkalemic periodic paralysis is an autosomal dominant clinical condition where there is a mutation in gene located at 17q23 that regulates the production of protein SCN4A. SCN4A is an important component of sodium channels in skeletal muscles. During exercise, sodium channels would open to allow influx of sodium into the muscle cells for depolarization to occur. But in hyperkalemic periodic paralysis, sodium channels are slow to close after exercise, causing excessive influx of sodium and displacement of potassium out of the cells.[14][21]
Rare causes of hyperkalemia are discussed as follows. Acute digitalis overdose such as digoxin toxicity may cause hyperkalemia[22] through the inhibition of sodium-potassium-ATPase pump.[14] Massive blood transfusion can cause hyperkalemia in infants due to leakage of potassium out of the red blood cells during storage.[14] Giving succinylcholine to people with conditions such as burns, trauma, infection, prolonged immobilisation can cause hyperkalemia due to widespread activation of acetylcholine receptors rather than a specific group of muscles. Arginine hydrochloride is used to treat refractory metabolic alkalosis. The arginine ions can enter cells and displace potassium out of the cells, causing hyperkalemia. Calcineurin inhibitors such as cyclosporine, tacrolimus, diazoxide, and minoxidil can cause hyperkalemia.[14] Box jellyfish venom can also cause hyperkalemia.[23]
Excessive intake
[edit]Excessive intake of potassium is not a primary cause of hyperkalemia because the human body usually can adapt to the rise in the potassium levels by increasing the excretion of potassium into urine through aldosterone hormone secretion and increasing the number of potassium secreting channels in kidney tubules.[14] Acute hyperkalemia in infants is also rare even though their body volume is small, with accidental ingestion of potassium salts or potassium medications. Hyperkalemia usually develops when there are other co-morbidities such as hypoaldosteronism and chronic kidney disease.[14]
Pseudohyperkalemia
[edit]Pseudohyperkalemia occurs when the measured potassium level is falsely elevated.[24] This condition is usually suspected when the patient is clinically well without any ECG changes. Mechanical trauma during blood drawing can cause potassium leakage out of the red blood cells due to haemolysis of the blood sample.[24] Repeated fist clenching during the blood draw can cause a transient rise in potassium levels.[25] Prolonged length of blood storage can also increase serum potassium levels. Hyperkalemia may become apparent when a person's platelet concentration is more than 500,000/microL in a clotted blood sample (serum blood sample). Potassium leaks out of platelets after clotting has occurred. A high white cell count (greater than 120,000/microL) in people with chronic lymphocytic leukemia increases the fragility of red blood cells, thus causing pseudohyperkalemia during blood processing. This problem can be avoided by processing serum samples, because clot formation protects the cells from haemolysis during processing. A familial form of pseudohyperkalemia, a benign condition characterised by increased serum potassium in whole blood stored at cold temperatures, also exists. This is due to increased potassium permeability in red blood cells.[14]
Mechanism
[edit]Physiology
[edit]Potassium is the most abundant intracellular cation and about 98% of the body's potassium is found inside cells, with the remainder in the extracellular fluid including the blood. Membrane potential is maintained principally by the concentration gradient and membrane permeability to potassium with some contribution from the Na+/K+ pump. The potassium gradient is critically important for many physiological processes, including maintenance of cellular membrane potential, homeostasis of cell volume, and transmission of action potentials in nerve cells.[13]
Potassium is eliminated from the body through the gastrointestinal tract, kidney and sweat glands. In the kidneys, elimination of potassium is passive (through the glomeruli), and reabsorption is active in the proximal tubule and the ascending limb of the loop of Henle. There is active excretion of potassium in the distal tubule and the collecting duct; both are controlled by aldosterone. In sweat glands potassium elimination is quite similar to the kidney; its excretion is also controlled by aldosterone.[medical citation needed]
Regulation of serum potassium is a function of intake, appropriate distribution between intracellular and extracellular compartments, and effective bodily excretion. In healthy individuals, homeostasis is maintained when cellular uptake and kidney excretion naturally counterbalance a patient's dietary intake of potassium.[26][27] When kidney function becomes compromised, the ability of the body to effectively regulate serum potassium via the kidney declines. To compensate for this deficit in function, the colon increases its potassium secretion as part of an adaptive response. However, serum potassium remains elevated as the colonic compensating mechanism reaches its limits.[28][29]
Elevated potassium
[edit]Hyperkalemia develops when there is excess production (oral intake, tissue breakdown) or ineffective elimination of potassium. Ineffective elimination can be hormonal (in aldosterone deficiency) or due to causes in the kidney that impair excretion.[30]
Increased extracellular potassium levels result in depolarization of the membrane potentials of cells due to the increase in the equilibrium potential of potassium. This depolarization opens some voltage-gated sodium channels, but also increases the inactivation at the same time. Since depolarization due to concentration change is slow, it never generates an action potential by itself; instead, it results in accommodation. Above a certain level of potassium the depolarization inactivates sodium channels, opens potassium channels, thus the cells become refractory. This leads to the impairment of neuromuscular, cardiac, and gastrointestinal organ systems. Of most concern is the impairment of cardiac conduction, which can cause ventricular fibrillation and/or abnormally slow heart rhythms.[13]
Diagnosis
[edit]To gather enough information for diagnosis, the measurement of potassium must be repeated, as the elevation can be due to hemolysis in the first sample. The normal serum level of potassium is 3.5 to 5 mmol/L. Generally, blood tests for kidney function (creatinine, blood urea nitrogen), glucose and occasionally creatine kinase and cortisol are performed. Calculating the trans-tubular potassium gradient can sometimes help in distinguishing the cause of the hyperkalemia.[medical citation needed]
Also, electrocardiography (ECG) may be performed to determine if there is a significant risk of abnormal heart rhythms.[13] Physicians taking a medical history may focus on kidney disease and medication use (e.g. potassium-sparing diuretics), both of which are known causes of hyperkalemia.[13]
Definitions
[edit]Normal serum potassium levels are generally considered to be between 3.5 and 5.3 mmol/L.[3] Levels above 5.5 mmol/L generally indicate hyperkalemia, and those below 3.5 mmol/L indicate hypokalemia.[1][3]
ECG findings
[edit]With mild to moderate hyperkalemia, there is prolongation of the PR interval and development of peaked T waves.[13] Severe hyperkalemia results in a widening of the QRS complex, and the ECG complex can evolve to a sinusoidal shape.[31] There appears to be a direct effect of elevated potassium on some of the potassium channels that increases their activity and speeds membrane repolarisation. Also, (as noted above), hyperkalemia causes an overall membrane depolarization that inactivates many sodium channels. The faster repolarisation of the cardiac action potential causes the tenting of the T waves, and the inactivation of sodium channels causes a sluggish conduction of the electrical wave around the heart, which leads to smaller P waves and widening of the QRS complex.[medical citation needed] Some of potassium currents are sensitive to extracellular potassium levels, for reasons that are not well understood. As the extracellular potassium levels increase, potassium conductance is increased so that more potassium leaves the myocyte in any given time period.[32] To summarize, classic ECG changes associated with hyperkalemia are seen in the following progression: peaked T wave, shortened QT interval, lengthened PR interval, increased QRS duration, and eventually absence of the P wave with the QRS complex becoming a sine wave. Bradycardia, junctional rhythms and QRS widening are particularly associated with increased risk of adverse outcomes[33]
The serum potassium concentration at which electrocardiographic changes develop is somewhat variable. Although the factors influencing the effect of serum potassium levels on cardiac electrophysiology are not entirely understood, the concentrations of other electrolytes, as well as levels of catecholamines, play a major role.[medical citation needed]
ECG findings are not a reliable finding in hyperkalemia. In a retrospective review, blinded cardiologists documented peaked T-waves in only 3 of 90 ECGs with hyperkalemia. Sensitivity of peaked-Ts for hyperkalemia ranged from 0.18 to 0.52 depending on the criteria for peak-T waves.[medical citation needed]
Prevention
[edit]Preventing recurrence of hyperkalemia typically involves reduction of dietary potassium, removal of an offending medication, and/or the addition of a diuretic (such as furosemide or hydrochlorothiazide).[13] Sodium polystyrene sulfonate and sorbitol (combined as Kayexalate) are occasionally used on an ongoing basis to maintain lower serum levels of potassium though the safety of long-term use of sodium polystyrene sulfonate for this purpose is not well understood.[13]
High dietary sources include vegetables such as avocados,[34][35] tomatoes and potatoes, fruits such as bananas, oranges and nuts.[36]
Treatment
[edit]Emergency lowering of potassium levels is needed when new arrhythmias occur at any level of potassium in the blood, or when potassium levels exceed 6.5 mmol/L. Several agents are used to temporarily lower K+ levels. The choice depends on the degree and cause of the hyperkalemia, and other aspects of the person's condition.
Myocardial excitability
[edit]Calcium (calcium chloride or calcium gluconate) increases threshold potential through a mechanism that is still unclear, thus restoring normal gradient between threshold potential and resting membrane potential, which is elevated abnormally in hyperkalemia. A standard ampule of 10% calcium chloride is 10 mL and contains 6.8 mmol of calcium. A standard ampule of 10% calcium gluconate is also 10 mL but has only 2.26 mmol of calcium. Clinical practice guidelines recommend giving 6.8 mmol for typical EKG findings of hyperkalemia.[13] This is 10 mL of 10% calcium chloride or 30 mL of 10% calcium gluconate.[13] Though calcium chloride is more concentrated, it is caustic to the veins and should only be given through a central line.[13] Onset of action is less than one to three minutes and lasts about 30–60 minutes.[13] The goal of treatment is to normalise the EKG and doses can be repeated if the EKG does not improve within a few minutes.[13]
Some textbooks suggest that calcium should not be given in digoxin toxicity as it has been linked to cardiovascular collapse in humans and increased digoxin toxicity in animal models. Recent literature questions the validity of this concern.[medical citation needed]
Temporary measures
[edit]Several medical treatments shift potassium ions from the bloodstream into the cellular compartment, thereby reducing the risk of complications. The effect of these measures tends to be short-lived, but may temporise the problem until potassium can be removed from the body.[37]
- Insulin (e.g. intravenous injection of 10 units of regular insulin along with 50 mL of 50% dextrose to prevent the blood sugar from dropping too low) leads to a shift of potassium ions into cells, secondary to increased activity of the sodium-potassium ATPase.[38] Its effects last a few hours, so it sometimes must be repeated while other measures are taken to suppress potassium levels more permanently. The insulin is usually given with an appropriate amount of glucose to help prevent hypoglycemia following the insulin administration, though hypoglycaemia remains common especially in the context of acute or chronic renal impairment[39] and capillary blood glucose measurements should be taken regularly after administration to identify this.
- Salbutamol (albuterol), a β2-selective catecholamine, is administered by nebuliser (e.g. 10–20 mg). This medication also lowers blood levels of K+ by promoting its movement into cells, and will work within 30 minutes.[38] It is recommended to use 20 mg for maximum potassium lowering effect, but to use lower doses if the patient is tachycardic or has ischaemic heart disease. Note that 12-40% of patients do not respond to salbutamol therapy for reasons unknown, especially if on beta-blockers, so it should not be used as monotherapy[40]
- Sodium bicarbonate may be used with the above measures if it is believed the person has metabolic acidosis,[3] though time to effectiveness is longer and its use is controversial.
Elimination
[edit]Severe cases require hemodialysis, which are the most rapid methods of removing potassium from the body.[38] These are typically used if the underlying cause cannot be corrected swiftly while temporising measures are instituted or there is no response to these measures.
Loop diuretics (furosemide, bumetanide, torasemide) and thiazide diuretics (e.g., chlortalidone, hydrochlorothiazide, or chlorothiazide) can increase kidney potassium excretion in people with intact kidney function.[38]
Potassium can bind to a number of agents in the gastrointestinal tract.[41][27] Sodium polystyrene sulfonate with sorbitol (Kayexalate) has been approved for this use and can be given by mouth or rectally.[38] However, high quality evidence to demonstrate the effectiveness of sodium polystyrene are lacking, and use of sodium polystyrene sulfonate, particularly with high sorbitol content, is uncommonly but convincingly associated with colonic necrosis.[42][43][44] There are no systematic studies (>6 months) looking at the long-term safety of this medication.[45]
Patiromer is taken by mouth and works by binding free potassium ions in the gastrointestinal tract and releasing calcium ions for exchange, thus lowering the amount of potassium available for absorption into the bloodstream and increasing the amount lost via the feces.[13][46] The net effect is a reduction of potassium levels in the blood serum.[13]
Sodium zirconium cyclosilicate is a medication that binds potassium in the gastrointestinal tract in exchange for sodium and hydrogen ions.[13] Onset of effects occurs in one to six hours.[47] It is taken by mouth.[47]
Epidemiology
[edit]Hyperkalemia is rare among those who are otherwise healthy.[6] Among those who are in hospital, rates are between 1% and 2.5%.[2]
Society and culture
[edit]In the United States, hyperkalemia is induced by lethal injection in capital punishment cases. Potassium chloride is the last of the three drugs administered and actually causes death. Injecting potassium chloride into the heart muscle disrupts the signal that causes the heart to beat. This same amount of potassium chloride would do no harm if taken orally and not injected directly into the blood.[citation needed]
References
[edit]- ^ a b c d e f g h i j k l m n o p q r Lehnhardt A, Kemper MJ (March 2011). "Pathogenesis, diagnosis and management of hyperkalemia". Pediatric Nephrology. 26 (3): 377–384. doi:10.1007/s00467-010-1699-3. PMC 3061004. PMID 21181208.
- ^ a b c d e f g McDonald TJ, Oram RA, Vaidya B (20 October 2015). "Investigating hyperkalaemia in adults". BMJ. 351: h4762. doi:10.1136/bmj.h4762. PMID 26487322. S2CID 206907572.
- ^ a b c d e f g h i j k l Soar J, Perkins GD, Abbas G, Alfonzo A, Barelli A, Bierens JJ, Brugger H, Deakin CD, Dunning J, Georgiou M, Handley AJ, Lockey DJ, Paal P, Sandroni C, Thies KC, Zideman DA, Nolan JP (October 2010). "European Resuscitation Council Guidelines for Resuscitation 2010 Section 8. Cardiac arrest in special circumstances: Electrolyte abnormalities, poisoning, drowning, accidental hypothermia, hyperthermia, asthma, anaphylaxis, cardiac surgery, trauma, pregnancy, electrocution". Resuscitation. 81 (10): 1400–1433. doi:10.1016/j.resuscitation.2010.08.015. PMID 20956045.
- ^ a b Pathy MJ (2006). "Appendix 1: Conversion of SI Units to Standard Units". Principles and practice of geriatric medicine. Vol. 2 (4th ed.). Chichester [u.a.]: Wiley. p. Appendix. doi:10.1002/047009057X.app01. ISBN 9780470090558.
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