Symptomatic hypercalcemia due to painless thyroiditis after unilateral adrenalectomy in a patient with Cushing's syndrome

We report a 53-year-old woman with Cushing's syndrome due to an adrenocortical adenoma, who underwent unilateral adrenalectomy and developed symptomatic hypercalcemia during the thyrotoxic period of painless thyroiditis, while tapering off a daily supplemented dose of cortisol. A study of patients with thyrotoxicosis and hypoadrenalism at our institute revealed that mild hypercalcemia was present in 9.9% of those with thyrotoxicosis and 5.0% of those with hypoadrenalism. The present case suggests that the simultaneous occurrence of thyrotoxicosis and hypoadrenalism may lead to overt hypercalcemia due to a synergistic increase in bone resorption and impaired urinary excretion of calcium.