Hyperkalémia

Hyperkalémia is a condition characterized by an elevated concentration of potassium in the blood. Potassium is essential for nerve and muscle function, including the electrical activity of the heart. In adults, a serum potassium level above about 5.0 milliequivalents per liter is commonly used to define hyperkalémia, though clinical significance depends on the rate of rise and accompanying conditions.

Causes of hyperkalémia fall into several categories. Reduced renal potassium excretion is a major factor, especially in chronic kidney disease or acute kidney injury. Medications that impair potassium elimination, such as ACE inhibitors, ARBs, potassium-sparing diuretics, nonsteroidal anti-inflammatory drugs, and certain drugs like heparin, can contribute. Increased potassium intake is usually a concern only with impaired excretion or rapid shifts. Intracellular to extracellular potassium shifts can occur with acidosis, insulin deficiency, tissue injury, or certain medications. Pseudohyperkalémia may occur due to hemolysis or sample mishandling.

Clinical features range from asymptomatic to symptoms such as muscle weakness or paresthesias. The most serious risk is cardiac arrhythmia. Electrocardiographic changes include tall peaked T waves, shortened QT interval, widening of the QRS complex, and, in severe cases, a sine-wave pattern that can progress to ventricular fibrillation or asystole.

Diagnosis relies on a confirmed elevated serum potassium and clinical context. Management is guided by the severity and presence of ECG changes. In patients with ECG abnormalities or high risk, rapid membrane stabilization with intravenous calcium is recommended. Potassium should be shifted into cells using insulin with glucose, beta-agonists, and bicarbonate if acidosis is present. Potassium removal can be achieved with diuretics, cation-exchange resins, or newer potassium binders, and in severe or refractory cases or in kidney failure, dialysis. Prevention focuses on at-risk populations, medication review, and regular monitoring of potassium levels.