Magnesium: Its Proven and Potential Clinical Significance

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South Med J. 2001;94(12) 

In This Article

Diagnosis of Magnesium Deficiency

The serum magnesium level correlates poorly with total body stores.[4] As a result, there have been several intracellular assays of magnesium from muscle biopsy, lymphocytes, and red blood cells. These assays include nuclear magnetic resonance (NMR) spectroscopy[9] and ion-specific electrode measures.[10] However, these tests are expensive and often require fresh specimens and are therefore not clinically applicable at present. For these reasons, despite its limitations, serum magnesium determination is deemed of value in assessing changes in magnesium status and is the entry level test for the evaluation of possible disorders of magnesium metabolism. When the serum magnesium level is low, intracellular magnesium is also low.[11,12] However, many patients may have normal serum magnesium levels but be intracellularly depleted.[6,13] Therefore, if the serum magnesium level is low, the patient is deficient; however, if it is normal, the patient may still be magnesium deficient.