Lab

Serum Magnesium

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Serum Magnesium, Serum Mg

  • See Also
  1. Hypermagnesemia
  2. Hypomagnesemia
  3. Magnesium Sulfate
  • Precautions
  1. Serum Magnesium represents only 1 to 1.5% of total body Magnesium (of which only 50% is active, ionized)
  2. Magnesium levels tend to vary widely (e.g. with respiration) and single values are unlikely to be useful
  3. Serum Potassium tends to be a surrogate marker for Serum Magnesium
    1. Hyperkalemia is typically accompanied by hpermagnesemia
    2. Hypokalemia is typically accompanied by Hypomagnesemia
      1. Consider empiric Magnesium Replacement at the time of Potassium Replacement
  • Labs
  1. Ionized Magnesium is most accurate but is not widely available
  2. Serum Magnesium
    1. Normal: 1.8 - 3.0 mg/dl
  • Causes
  • Abnormal
  1. Serum Magnesium >3.0 mg/dl
    1. See Hypermagnesemia
  2. Serum Magnesium <1.8 mg/dl
    1. See Hypomagnesemia
  • References
  1. Orman and Slovis in Herbert (2018) EM:Rap 18(8): 13-4