Hypokalemia
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Basics

Description

Hypokalemia is defined as a serum potassium concentration <3.5 mEq/L (normal range, 3.5–5 mEq/L).

Epidemiology

Predominant sex: Male = Female

Incidence
  • Electrolyte abnormality is commonly encountered in clinical practice (1).
  • 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
  • Associated risk after bariatric surgery

Risk Factors


Genetics
Some rare, familial disorders 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”).

Etiology

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)

Commonly Associated Conditions

Acute GI illnesses with severe vomiting or diarrhea

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