Hypomagnesemia

Hypomagnesemia is a topic covered in the Washington Manual of Medical Therapeutics.

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General Principles

  • A serum magnesium <1.3 mEq/L defines hypomagnesemia.
  • Hypomagnesemia is most commonly caused by impaired intestinal absorption and increased renal excretion.
    • Decreased intestinal absorption occurs in malnutrition, as is common in chronic alcoholics or any malabsorption syndrome. Magnesium can also be lost through prolonged diarrhea and nasogastric aspiration. Hypomagnesemia has been described with chronic use of proton pump inhibitors, presumably due to impaired intestinal absorption.
    • Increased renal excretion of magnesium can occur from increased renal tubular flow (as occurs with osmotic diuresis) as well as impaired tubular function (as seen with resolving acute tubular necrosis, loop diuretics, and Bartter and Gitelman syndromes).
  • Drugs. Several medications similarly induce defects in tubular magnesium transport including aminoglycosides, amphotericin B, cisplatin, pentamidine, and cyclosporine.

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General Principles

  • A serum magnesium <1.3 mEq/L defines hypomagnesemia.
  • Hypomagnesemia is most commonly caused by impaired intestinal absorption and increased renal excretion.
    • Decreased intestinal absorption occurs in malnutrition, as is common in chronic alcoholics or any malabsorption syndrome. Magnesium can also be lost through prolonged diarrhea and nasogastric aspiration. Hypomagnesemia has been described with chronic use of proton pump inhibitors, presumably due to impaired intestinal absorption.
    • Increased renal excretion of magnesium can occur from increased renal tubular flow (as occurs with osmotic diuresis) as well as impaired tubular function (as seen with resolving acute tubular necrosis, loop diuretics, and Bartter and Gitelman syndromes).
  • Drugs. Several medications similarly induce defects in tubular magnesium transport including aminoglycosides, amphotericin B, cisplatin, pentamidine, and cyclosporine.

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