Magnesium metabolism in healthy subjects.

Magnesium metabolism was studied in 106 apparently healthy subjects aged between 15 and 80 years. The serum magnesium values had a gaussian distribution with a narrow range and with no age or sex dependence. The basal, urinary magnesium excretion was greater in men than in women at all ages and decreased with age. The magnesium and calcium excretions were closely correlated in both sexes. The fractional, gastrointestinal absorption of magnesium, assessed by a newly developed technique using the radionuclide 28Mg, compared favourably with that in earlier balance and tracer studies. The intracellular magnesium content, estimated in muscle specimens obtained by percutaneous biopsies, was not correlated to age or sex. A magnesium-loading test was performed, and the normal range for magnesium retention was calculated. No correlation was demonstrated between different magnesium parameters within the normal range in these subjects.