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Emergency: requires immediate attention
Other Resources UpToDate PubMed
Emergency: requires immediate attention


Contributors: Sanuja Bose BS, BA, Abhijeet Waghray MD
Other Resources UpToDate PubMed


Hyperkalemia is a condition of elevated serum potassium concentration (> 5.5 mmol/L) due to increased potassium release from cells, excess potassium intake, or more commonly, reduced excretion of urinary potassium. This may be caused by excessive load (administration or intake of potassium) with potassium salts, blood transfusions (not fresh), or extreme intake of water treated with potassium-based water softener; impaired excretion, as seen in renal failure; or use of potassium-sparing diuretic drugs, NSAIDs, angiotensin-converting enzyme (ACE) inhibitors, aldosterone-suppressing therapies, or other drug-induced effects (such as digitalis toxicity). Other causes include Addison disease, decreased insulin with high osmolality, acidosis (eg, diabetic ketoacidosis), dehydration, hyperventilation, pregnancy, and malignant hyperthermia.

Signs and symptoms include muscle weakness, paralysis, hypothermia, and cardiac abnormalities (irregular conduction and arrhythmias).

ECG changes of hyperkalemia do not reliably correlate with potassium levels, but mild elevation (5.5-6.5 mmol/L) may cause peaked T waves, shortened QT interval, and ST-segment depression.

At higher levels of potassium (< 8.0 mmol/L), the ECG may demonstrate peaked T waves, PR prolongation with decreased P waves, and widening QRS. At potassium levels > 8.0 mmol/L, P waves may be absent, with progressively widening QRS, and intravesicular / fascicular / bundle branch block development, progressing to a sine wave pattern, followed by ventricular fibrillation or asystole. It is important to note that approximately 50% of patients do not have ECG changes even with serum potassium > 6.0 mmol/L, however. Still, the absolute level of serum potassium is important in predicting morbidity and mortality, along with the rate at which it is reached and how long the patient remains hyperkalemic.

Pseudohyperkalemia can be caused by improper blood drawing techniques, hemolysis, tourniquet use, and clenched fists.

In addition to acquired hyperkalemia, hyperkalemic periodic paralysis is an autosomal dominant inherited disorder that causes fluctuating potassium levels and episodic muscle weakness when potassium levels are high.


E87.5 – Hyperkalemia

14140009 – Hyperkalemia

Look For

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Diagnostic Pearls

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Differential Diagnosis & Pitfalls

Causes of hyperkalemia:

Increased potassium release from cells Increased potassium intake
  • Excess consumption of potassium-rich foods (banana, potatoes, melons, citrus, avocados)
  • Salt substitutes (common in patients with CKD)
Reduced urinary potassium excretion
  • Oliguric renal failure
  • Acute or chronic kidney disease
  • Hyporeninemic hypoaldosteronism
  • Type 4 renal tubular acidosis
  • Drugs – angiotensin inhibitors, NSAIDs, calcineurin inhibitors (cyclosporine, tacrolimus), heparin, potassium-sparing diuretics
  • Mineralocorticoid deficiency or resistance
  • Cortical collecting tubule defect

Best Tests

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Management Pearls

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Drug Reaction Data

Below is a list of drugs with literature evidence indicating an adverse association with this diagnosis. The list is continually updated through ongoing research and new medication approvals. Click on Citations to sort by number of citations or click on Medication to sort the medications alphabetically.

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Last Reviewed:05/08/2019
Last Updated:05/13/2019
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Emergency: requires immediate attention
A medical illustration showing key findings of Hyperkalemia : Fasciculations, Hyperkalemia, Muscle weakness, Heart palpitations, Paralysis, Paresthesias
Copyright © 2023 VisualDx®. All rights reserved.