Hypokalemia is a topic covered in the 5-Minute Clinical Consult.

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Hypokalemia is defined as a serum potassium concentration <3.5 mEq/L (normal range, 3.5 to 5.0 mEq/L).

  • Mild hypokalemia (serum potassium 3.0 to 3.5 mEq/L)
  • Moderate hypokalemia (serum potassium 2.5 to 3.0 mEq/L)
  • Severe hypokalemia (serum potassium <2.5 mEq/L)


Predominant sex: male = female

  • Electrolyte abnormality is commonly encountered in clinical practice and in the elderly.
  • Found in >20% of hospitalized patients (when defined as potassium <3.6 mEq/L)
  • Higher incidence (5–20%) in individuals with eating disorders
  • >10% of inpatients with alcoholism
  • Higher incidence in patients with AIDS
  • Higher incidence in patients receiving diuretics
  • 12–18% in patients with CKD
  • Associated risk after bariatric surgery

Etiology and Pathophysiology

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, β2-agonists), hypokalemic periodic paralysis, intoxications (theophylline, caffeine, barium, toluene), refeeding syndrome (1)[C]
  • Renal potassium loss
    • Drugs: diuretics (especially loop and thiazides), amphotericin B, aminoglycosides
    • 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
    • Osmotic diuresis (e.g., poorly controlled diabetes)
    • Renal tubular acidosis (type I and II)
    • Magnesium depletion
  • Glucocorticoid excess states: Cushing syndrome, exogenous steroids, ectopic adrenocorticotrophic hormone production, 11-β-hydroxysteroid dehydrogenase deficiency, refeeding syndrome

Some rare, familial disorders can cause hypokalemia.

  • Familial hypokalemic periodic paralysis: hypokalemia after a high-carbohydrate or high-sodium meal or after exercise
  • Congenital adrenogenital syndromes
  • Liddle syndrome: increases K+ secretion
  • Familial interstitial nephritis

General Prevention

When initiating a diuretic, especially loop and thiazide diuretics, advise patients to increase their dietary potassium intake (see “Diet”).

Commonly Associated Conditions

  • Acute GI illnesses with severe vomiting or diarrhea
  • Increased risk of cardiac arrhythmias; atrial fibrillation
  • Hypokalemia is a predictor of development of severe alcohol withdrawal syndrome.

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