LITHIUM-CARBONATE THERAPY IS NOT A RISK FACTOR FOR OSTEOPOROSIS

Lithium carbonate is a widely used drug for affective disorders. It ma y effect calcium metabolism and alter parathyroid physiology by causin g hypersecretion of parathyroid hormone. Patients treated with this me dication might therefore be predisposed to osteoporosis. The purpose o f this study was to evaluate the effect of either short- or long-term lithium carbonate therapy on parameters of bone metabolism. Parathyroi d function and indices of bone metabolism were assessed in 23 patients treated for affective disorders. 10 patients were treated for 0.4-1.0 year (Group 1), and 13 patients were treated for more than 3 years (G roup 2). In all subjects, bone mineral density measurements in the hip and lumbar spine regions were performed using dual energy X-ray absor ptiometry. Serum thyroid hormone, PTH, LH, testosterone and urine OH-p roline, free cortisol, calcium and phosphate excretion were measured. The two groups were well matched for sex, weight, calcium intake, lith ium levels and smoking habits, although Group 2 was slightly older. No differences between the two groups were noted in either bone mineral density or other parameters that were assessed. Urinary OH-proline was elevated similarly in both groups. Our results did not detect any eff ect on bone density after short- or long-term lithium carbonate therap y, although the data does suggest an increase in bone turnover associa ted with this treatment. Thus, short- or long-term treatment with lith ium is not associated with increased risk for osteoporosis.