Most common causes:

• Decreased intake: Deficient diet in alcoholics and elderly; anorexia nervosa
• GI loss: Vomiting, diarrhea, nasogastric tubes, laxative abuse, fistulas, villous adenoma, ureterosigmoidostomy, malabsorption, chemotherapy, radiation enteropathy, bulimia
• Intracellular shift of potassium: Metabolic alkalosis, insulin excess, β-adrenergic catecholamine excess (acute stress, B₂ agonists [2]), hypokalemic periodic paralysis, intoxications (theophylline, caffeine, barium, toluene)
• Renal potassium loss:
  • Drugs: Diuretics (especially loop and thiazides), amphotericin B, aminoglycosides (3,4,5)
  • Mineralocorticoid-excess states: Primary hyperaldosteronism; secondary hyperaldosteronism (congestive heart failure [CHF], cirrhosis, nephrotic syndrome, malignant hypertension, renin-producing tumors); renovascular hypertension; Bartter syndrome; Gitelman syndrome; congenital adrenogenital syndromes; exogenous mineralocorticoids (glycyrrhizic acid in licorice, carbenoxolone, steroids in nasal sprays); Liddle syndrome; vasculitis
• Glucocorticoid-excess states: Cushing syndrome, exogenous steroids, ectopic adrenocorticotrophic hormone (ACTH) production, II B hydroxysteroid dehydrogenase deficiency.
• Renal tubular acidosis (type I and II):
  • Leukemia
  • Magnesium depletion
  • Thyrotoxic hypokalemic paralysis
• Osmotic diuresis (e.g., poorly controlled diabetes)