Hypokalemia

Causes

Kidney potassium loss

• Excess mineralocorticoid activity
  • Mineralocorticoid disorder
  • Renal artery stenosis
  • Liddle syndrome
• Potassium-wasting diuretics
  • Loop diuretics
  • Thiazide diuretics
• Tubulopathy
  • Bartter syndrome, Gitelman syndrome
  • Fanconi syndrome
  • Potassium wasting due to hypomagnesemia

Gastrointestinal (GI) potassium loss

• Diarrhea
  • Laxative abuse
• Vomiting
  • Nasogastric/orogastric (NG/OG) suction

Intracellular shifts (movement of potassium into cells)

• Alkalosis
• Insulin
• β-agonists (e.g., albuterol)
• Hypokalemic periodic paralysis (AKA: PP, hypoKPP, hypoPP)

Signs and symptoms

• Usually asymptomatic
• Muscle cramps, weakness
• Cardiac arrhythmias (esp., ventricular tachycardia, ventricular fibrillation)
• Can decrease ability to concentrate urine

Evaluation

• If hypertension present, consider evaluation for mineralocorticoid disorder, renal artery stenosis, Liddle’s syndrome, etc.
• Laboratory workup:
  • Evaluate for other electrolyte derangements, esp. hypomagnesemia
  • Alkalosis
• EKG if severe (consider if <2.5 mEq/L, esp. if <2 mEq/L)

Treatment

• Treat underlying cause
• Oral potassium chloride replacement is easiest and safest for mild hypokalemia (3-3.5 mEq/L)
• IV repletion for severe/symptomatic or if unable to tolerate PO