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Hyperkalemia is a potentially life-threatening electrolyte disorder defined as serum potassium levels above 5.5 mEq/L. It can cause dangerous cardiac arrhythmias and requires prompt recognition and treatment. Common causes include kidney disease, medications like ACE inhibitors, and tissue breakdown.
Hyperkalemia results from impaired potassium excretion by the kidneys, excessive potassium intake, or cellular shifts that move potassium from intracellular to extracellular spaces. The elevated extracellular potassium alters the resting membrane potential of cardiac myocytes, affecting sodium channel inactivation and potentially leading to fatal arrhythmias. The heart is particularly sensitive to potassium changes, with progressive ECG changes occurring as levels rise.
Diagnosis relies on serum potassium measurement while monitoring for characteristic ECG changes including peaked T waves, widened QRS complexes, and sine wave patterns. Treatment urgency depends on potassium level and ECG findings, with severe cases requiring immediate cardiac membrane stabilization with calcium, followed by measures to shift potassium intracellularly and enhance elimination. The underlying cause must be identified and addressed, whether medication-related, renal dysfunction, or other metabolic disorders.