Lithium effects on calcium, magnesium and phosphate in man: effects on balance, bone mineral content, faecal and urinary excretion

Calcium, magnesium and phosphate metabolism was studied in lithium-treated patients, using a metabolic balance technique. Two groups of patients participated in the study: 1) Patients who were to start on a prophylactic lithium treatment, and 2) Long-term lithium-treated patients whose treatment was to be terminated. Lithium treatment produced a positive balance in both calcium, phosphate and magnesium. By continuous lithium treatment the effect on magnesium wore off, whereas the effect on calcium and phosphate persisted. In urine, lithium induced a decrease in both calcium and phosphate excretion, whereas the excretion of magnesium was increased. Bone mineral content was measured by photon absorption, and lithium treatment resulted in a decrease in bone mineral content occurring within the first 6 months of lithium treatment. In the patients, bioavailability of the Li2CO3 preparation was found to be about 95%, and the patients contained about one 24-h dose of lithium just before the next dose of lithium was administered.