Lithium's effect of parathyroid hormone.

Lithium has been reported to raise serum calcium and lower serum phosphate concentrations and to increase urinary calcium excretion. Because these changes may be effects of parathyroid hormone (PTH), PTH was measured in 19 patients receiving lithium. PTH was significantly higher in these patients than in 150 normal subjects. For all patients serum calcium concentrations correlated significantly with serum lithium concentrations. These results indicate that lithium may cause biochemical hyperparathyroidism. Secondary hyperparathyroidism in certain patients with lithium nephrotoxicity is also possible.