Hyperkalemia-General

Hyperkalemia is defined as a potassium concentration > 5.5 mEq/L.
Hyperkalemia is a true medical emergency. The most serious effect of hyperkalemia is cardiac toxicity, which does not correlate well with the plasma [K]. Earliest ECG changes include increased T wave amplitude with tall T waves (especially in leads V2-V3). More severe hyperkalemia results in a prolonged PR interval and QRS duration, atrioventricular conduction delay, and loss of P waves. The terminal event is usually ventricular fibrillation or asystole which are resistant to the treatment until hyperkalemia is corrected. Hyperkalemia causes also a partial depolarization of cell membranes, which is manifested as weakness that may progress to flaccid paralysis and hypoventilation.

Causes of hyperkalemia:

	Increased [K] intake (e.g. iatrogenic, rapid transfusion of relatively old blood).
	Transcellular shift (most common cause).
	Tumor lysis syndrome.
	Rhabdomyolysis, intravascular hemolysis.
	Metabolic acidosis, especially in renal failure or in renal tubular acidosis. Less evident with lactic acidosis.
	Succinylcholine, especially in patients with anterior motor neuron disease, myopathies (see Myasthenia Gravis and Rare Syndromes for specific myopathies), burns or prolonged immobilization.
	Familial periodic paralysis.
	Impaired renal [K] excretion: Renal failure with GFR < 10 mL/min, and oliguria < 500 mL/day. Diabetic nephropathy. Adrenal insufficiency, hyporeninemic hypoaldosteronism.
	Drug related ([K]-sparing diuretics, ACE inhibitors, non-selective beta-blockers, cyclosporine, NSAIDs).