A serum potassium concentration <3.5 mEq/L (normal range, 3.5 to 5 mEq/L).

  • Mild: 3 to 3.5 mEq/L
  • Moderate: 2.5 to 3 mEq/L
  • Severe: <2.5 mEq/L


Predominant sex: male = female


  • Commonly encountered in clinical practice
  • >20% of hospitalized patients (when defined as potassium <3.6 mEq/L)
  • >10% of inpatients with alcoholism
  • 80% of patients receiving diuretics
  • 12–18% of patients with chronic kidney disease
  • Higher (5–20%) in individuals with eating disorders
  • Higher in patients with AIDS
  • 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, colorectal tumor, bowel diversion, 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), intensive exercise
  • Renal potassium loss
    • Drugs: diuretics especially loop and thiazides, amphotericin B, aminoglycosides, antipseudomonal penicillin (carbenicillin), high-dose penicillin, clay (bentonite)
    • Mineralocorticoid excess: primary hyperaldosteronism (Conn syndrome); secondary hyperaldosteronism (congestive heart failure, cirrhosis, nephrotic syndrome, malignant hypertension, renin-producing tumors); renovascular hypertension
    • Exogenous mineralocorticoids (glycyrrhizic acid in licorice, carbenoxolone, nasal steroids)
    • Osmotic diuresis (e.g., poorly controlled diabetes)
    • Types I and II renal tubular acidosis
  • Magnesium depletion
  • Glucocorticoid excess: Cushing syndrome, exogenous steroids, ectopic adrenocorticotrophic hormone production, refeeding syndrome
  • Diabetic ketoacidosis (DKA) treatment with delayed/inadequate potassium replenishment

Some rare, familial disorders that can cause hypokalemia

  • 11-β-Hydroxysteroid dehydrogenase deficiency
  • Apparent mineralocorticoid excess
  • Congenital adrenogenital syndromes
  • Familial glucocorticoid resistance
  • Familial hypokalemic periodic paralysis
  • Familial interstitial nephritis
  • Fanconi syndrome
  • Geller syndrome
  • Sodium channel mutations: Bartter, Gitelman, Liddle syndromes

Risk Factors

  • Higher systolic BP
  • Thiazide/loop diuretic use; ACE
  • Low serum cholesterol/low BMI
  • Higher albumin-to-creatinine ratio

General Prevention

When initiating a diuretic, monitor potassium level.

Commonly Associated Conditions

  • Acute GI illnesses with severe vomiting or diarrhea
  • Increased risk of cardiac arrhythmias
  • Predictor of development of severe alcohol withdrawal syndrome

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