Spurious

• Leakage from erythrocytes, marked thrombocytosis or leukocytosis
• Repeated fist clenching during phlebotomy
• Specimen from arm with K⁺ infusion

Decreased excretion

• Renal failure
• Renal secretory defects, eg, interstitial nephritis, sickle cell disease
• Hypoaldosteronism: hyporeninism (type IV renal tubular acidosis), eg, diabetic nephropathy, heparin, AIDS; adrenal insufficiency
• Drugs that inhibit K⁺ excretion (spironolactone, triamterene, ACE inhibitors, trimethoprim, NSAIDs)

Potassium shift out of cell

• Burns, rhabdomyolysis, hemolysis, severe infection, internal bleeding, vigorous exercise
• Metabolic acidosis
• Hypertonicity (solvent drag)
• Insulin deficiency
• Hyperkalemic periodic paralysis
• Drugs: digitalis toxicity, beta-adrenergic antagonists, succinylcholine, arginine

Excessive intake of K⁺

• Ingestion or iatrogenic