Hypokalemia

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Presentation :

• Characteristic findings include ileus, muscle cramps, rhabdomyolysis, and hypomagnesemia.

Pathophysiology :

• The most common causes of hypokalemia are vomiting, diarrhea, and diuretics
• Other causes include:
  • Primary aldosteronism (hypertension, urine [Cl–] >40 mEq/L, low plasma renin activity, and elevated aldosterone level)
  • Liddle Syndrome (HTN, metabolic alkalosis, and decreased renin/aldo levels)
  • Bartter syndrome (normal BP, hypoK, metabolic alkalosis, and elevated renin/aldo levels)
  • Gitelman syndrome (normal BP, hypoK, and hypoMg)
  • Inhaled β2-agonists (may lead to hypoK in certain clinical settings)
  • Hypokalemic Periodic Paralysis

Diagnostic Testing:

• ECGs may show U waves and flat or inverted T waves
• A spot urine potassium-creatinine ratio <13 mEq/g identifies hypokalemia secondary to lack of intake, transcellular shifts, or gastrointestinal losses
  • 24-hour urine potassium <30 mEq/24 h (30 mmol/d) is equivalent to above but is less practical to measure

Treatment :

• For severe hypokalemia, IV potassium chloride is indicated.
  • Total body potassium deficits are typically large (200 mEq for each 1 mEq/L decrease in plasma potassium).
• Hypomagnesemia and metabolic alkalosis should be corrected, if present

Prognosis:

References: