Acute adrenal insufficiency after unilateral adrenalectomy in Cushing's syndrome: precipitation by lithium-induced thyrotoxicosis during cortisol replacement.

We present a patient with Cushing's syndrome due to adrenocortical adenoma who developed acute adrenal insufficiency one month after unilateral adrenalectomy. She had received lithium carbonate for five years for manic-depressive psychosis. Drug administration was interrupted for 2 weeks postoperatively and was resumed thereafter. At the adrenal crisis, her serum free T4 and T3 levels were both high and serum TSH was subnormal. The thyrotoxicosis subsided spontaneously within 2 weeks. Serum thyroglobulin was markedly increased during the thyrotoxic state. Tests for antimicrosomal antibodies and antithyroglobulin antibodies remained negative. Examination of an open-biopsy specimen of the thyroid gland showed no evidence of thyroiditis. We considered the transient thyrotoxicosis to be due to lithium-induced thyrotoxicosis. Caution should therefore be exercised in administering lithium carbonate, especially when the patient's adrenal reserve is low, since even a mild degree of thyrotoxicosis can precipitate an acute adrenal crisis.