Hypokalemia
Basics
Description
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
Epidemiology
Predominant sex: male = female
Prevalence
- 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
Genetics
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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Citation
Domino, Frank J., et al., editors. "Hypokalemia." 5-Minute Clinical Consult, 33rd ed., Wolters Kluwer, 2025. Medicine Central, im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/1688585/0.5/Hypokalemia.
Hypokalemia. In: Domino FJF, Baldor RAR, Golding JJ, et al, eds. 5-Minute Clinical Consult. Wolters Kluwer; 2025. https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/1688585/0.5/Hypokalemia. Accessed December 1, 2024.
Hypokalemia. (2025). In Domino, F. J., Baldor, R. A., Golding, J., & Stephens, M. B. (Eds.), 5-Minute Clinical Consult (33rd ed.). Wolters Kluwer. https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/1688585/0.5/Hypokalemia
Hypokalemia [Internet]. In: Domino FJF, Baldor RAR, Golding JJ, Stephens MBM, editors. 5-Minute Clinical Consult. Wolters Kluwer; 2025. [cited 2024 December 01]. Available from: https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/1688585/0.5/Hypokalemia.
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