Description

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)

Epidemiology

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 penicillins (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 syndrome

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