Magnesium metabolism in human beings: studies with Mg²⁸

¹ Department of Medicine, University of Colorado School of Medicine, Denver, Colorado

Mg²⁸ was used to explore the kinetics of magnesium distribution in 9 normal individuals and in 16 patients with various diseases. When Mg²⁸ was given in 12–30 mEq of stable magnesium intravenously, plasma disappearance was rapid within the first several hours. In normal subjects a mean of 19.8% of the injected radioactivity was accounted for in the urine within 24 hours. Fecal excretion was negligible, although equilibration of Mg²⁸ in bile occurred within 18 hours. The specific activities of plasma and urine stabilized by the 18th hour, and showed only a gradual decrease thereafter. Exchangeable magnesium contents in normal subjects ranged between 2.6 and 5.3 mEq/kg of body weight—less than 16% of the estimated total body content of magnesium. Mg²⁸ exchanged very slowly with the stable ion in bone, muscle and erythrocytes. The results in patients with diabetes mellitus and hepatic diseases showed no striking differences from those obtained in normal subjects.

Note:
(With the Technical Assistance of Dale R. Harms and Jacqueline Z. Reardon)

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