Hyperparathyroidism in association with lithium therapy

This report describes a patient who was normocalcemic prior to treatment with lithium for manic-depressive psychosis, and documents progressive hypercalcemia ensuing over the subsequent six years of therapy. Elevated parathyroid hormone levels were found and neck exploration revealed a parathyroid adenoma. Unlike the usual case of hyperparathyroidism, the hypercalcemia was associated with a very low urinary excretion of calcium. The literature is reviewed and possible pathogenetic mechanisms discussed. Serum calcium should be determined before and periodically during lithium therapy. In susceptible individuals, hypercalcemia may occur due to the unmasking or development of parathyroid adenoma.