Case Report

Extreme Hyperkalemia

Authors: H A. Tran, MD


Hyperkalemia is a potentially fatal condition and is defined by a serum potassium level (K+) of greater than 5.5 mmol/L. The associated prevalence of cardiac arrhythmia increases directly with the degree of hyperkalemia. The danger in the majority of hyperkalemia cases is cardiac dysrhythmia, and often ventricular fibrillation or asystole is the terminating event. Although there are many previous reports addressing this threatening problem and associated therapeutic maneuvers, there have not been many previous reports citing the fatal concentration of hyperkalemia irrespective of the causes. However, it is uniformly accepted that a K+ concentration greater than 10.0 mmol/L is fatal unless urgent treatment is instituted. This report describes a case of nonfatal hyperkalemia of 14 mmol/L with intact survival and complete recovery. Potassium homeostasis is revisited, and some explanations are proffered regarding the protective mechanism against hyperkalemia, including transcellular flux, renal tubular function, and endocrine responses.

Key Points

* Hyperkalemia is potentially fatal and should be managed with urgency.

* Potassium level greater than 10 mmol/L is rare, and pseudohyperkalemia should be strongly considered, especially when clinically incongruent and when there is an absence of associated electrolyte abnormalities.

* Potassium homeostatic and protective mechanisms include a combination of cellular, renal, endocrine, and gastrointestinal responses. The latter is often not well appreciated.

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