Cimetidine does not correct circulating calcium and parathyroid hormone in primary hyperparathyroidism.

Thirteen patients with primary hyperparathyroidism were treated for 4-8 weeks with the H2-blocker cimetidine at a daily dose of 1 g. The drug had no effect on the serum concentrations of calcium or parathyroid hormone, nor did any of the patients improve clinically during the period of treatment. The recently reported efficacy of cimetidine in primary hyperparathyroidism is strongly questioned by the present results.