Hyperkalemia

Hyperkalemia is a condition in which the potassium level in the blood is higher than normal, typically defined as a serum potassium concentration above 5.0 mEq/L. It can range from mild to life-threatening, with higher levels increasing the risk of cardiac arrhythmias. Common causes include reduced renal potassium excretion (chronic kidney disease, acute kidney injury, hypoaldosteronism), medications that raise potassium (ACE inhibitors, ARBs, mineralocorticoid receptor antagonists, potassium-sparing diuretics, NSAIDs, heparin), tissue breakdown (rhabdomyolysis, burns), acidosis, and shifts of potassium from cells to the extracellular space (insulin deficiency, electrolyte disturbances, severe exercise). Most patients are asymptomatic. When symptoms occur, they may include muscle weakness, paresthesias, or fatigue. The most concerning signs are ECG changes and arrhythmias. Early ECG findings can include tall peaked T waves; as potassium rises, QRS complexes may widen and progress to sine-wave patterns, signaling imminent cardiac instability. Diagnosis relies on a confirmed elevated serum potassium level and assessment of cardiac conduction, kidney function, acid-base status, and contributing factors. Evaluation often includes an ECG and laboratory tests to check renal function, glucose, and bicarbonate. Management depends on severity and the presence of symptoms or ECG changes. For any patient with ECG changes or very high potassium, urgent treatment to stabilize the cardiac membrane is indicated, typically with intravenous calcium (calcium gluconate or calcium chloride). Potassium can then be shifted intracellularly using insulin with glucose, and/or beta-agonists, and corrected with bicarbonate if acidosis is present. Removal of potassium from the body can be achieved with diuretics if kidney function allows, cation-exchange resins (such as sodium polystyrene sulfonate) with caution, and newer agents like patiromer or sodium zirconium cyclosilicate. In severe or refractory cases, or when renal function is poor, renal replacement therapy (dialysis) may be necessary. Addressing underlying causes and adjusting or stopping offending medications are essential for prevention and long-term control. Prognosis improves with prompt treatment and management of risk factors.