II. 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

III. Labs

  1. Ionized Magnesium is most accurate but is not widely available
  2. Serum Magnesium
    1. Normal: 1.8 - 3.0 mg/dl

IV. Causes: Abnormal

  1. Serum Magnesium >3.0 mg/dl
    1. See Hypermagnesemia
  2. Serum Magnesium <1.8 mg/dl
    1. See Hypomagnesemia

V. References

  1. Orman and Slovis in Herbert (2018) EM:Rap 18(8): 13-4

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Ontology: Serum magnesium measurement (C0202125)

Definition (NCI) A quantitative measurement of the amount of magnesium present in a sample of serum.
Concepts Laboratory Procedure (T059)
SnomedCT 166760007, 144032008, 144043000, 166743002, 63571001
English Serum magnesium level, Serum Magnesium Measurement, serum magnesium measurement, serum magnesium measurement (lab test), magnesium level, Serum magnesium, Serum magnesium level (procedure), Serum Magnesium Test, Magnesium measurement, serum, Magnesium measurement, serum (procedure), Serum magnesium measurement
Dutch serum magnesium
French Magnésium sérique
German Magnesium im Serum
Italian Magnesio sierico
Portuguese Magnésio sérico
Spanish Magnesio en suero, medición de magnesio en suero (procedimiento), medición de magnesio en suero
Japanese 血清マグネシウム, ケッセイマグネシウム
Czech Hořčík v séru
Hungarian Szérum magnézium