Potentiation of Endocrine Adverse Effects of Lithium by Enalapril and Verapamil

Lithium, which is widely used in the management of patients with bipolar disorder, may alter the function of some endocrine organs, particularly the thyroid and parathyroid glands, as well as it may reduce the sensitivity of the kidneys to vasopressin. In most lithium-treated patients, endocrine abnormalities are limited to one endocrine organ and are observed only after long-term lithium therapy. The patient reported in this study developed hypothyroidism, hyperparathyroidism and nephrogenic diabetes insipidus. However, the last two disorders were induced by a small increase in plasma lithium levels as a result of the treatment with enalapril and verapamil. This case shows that patients at high risk of thyroid, parathyroid or renal disorders receiving lithium should not be treated with drugs known to interfere with plasma lithium levels.