Hyperkalemia

Excerpt

Hyperkalemia is a condition marked by a serum or plasma potassium concentration exceeding the upper limit of normal, typically greater than 5.0 to 5.5 mEq/L. Mild elevations are often asymptomatic, whereas severe hyperkalemia can precipitate life-threatening cardiac arrhythmias, muscle weakness, or paralysis. Clinical manifestations generally appear at levels above 6.0 mEq/L. However, the rate of change exerts greater influence than absolute values. Patients with chronic hyperkalemia, such as those with renal impairment, may tolerate higher potassium concentrations without symptoms, whereas acute shifts in potassium can induce severe manifestations at lower levels. Baseline potassium concentrations are higher in infants compared with children and adults.

Pseudohyperkalemia is a spurious elevation in measured potassium, commonly resulting from specimen collection, handling, hemolysis, or thrombocytosis. Serum potassium should be confirmed prior to the initiation of aggressive therapy when elevations lack a clear explanation. True hyperkalemia arises from increased potassium intake, transcellular shifts of intracellular potassium, or impaired renal excretion. Therapeutic urgency is determined by the severity of clinical manifestations, measured potassium levels, and underlying etiology.