Disorders of Potassium: Hyperkalemia

Abstract

Hyperkalemia is defined as a serum [K⁺] > 5.5 mEq/L. It is common in both outside and in-hospital patients. Hyperkalemia can be fatal if not recognized and treated. Proper treatment of hyperkalemia depends on the underlying cause. True hyperkalemia is caused by an excessive exogenous load of K⁺; it can also result from a decrease in cellular uptake, massive release following cell lysis, or a decrease in renal excretion. A number of drugs also cause hyperkalemia. Pseudohyperkalemia refers to a condition in which K⁺ is released from cells during venipuncture following prolonged application of a tourniquet in the arm. Hemolysis of red blood cells and an increased number of white blood cells (> 100,000 cells) and platelets (> 1,000,000 platelets) also release K⁺ and cause pseudohyperkalemia. A benign form of familial pseudohyperkalemia due to leakage of K⁺ from blood cells has been described in some families.