Vitamin D, calcium, and sarcoidosis.

Hypercalcemia occurs in about 10% of the patients with sarcoidosis; hypercalciuria is about three times more frequent. These abnormalities of calcium metabolism are due to dysregulated production of 1,25-(OH)2-D3 (calcitriol) by activated macrophages trapped in pulmonary alveoli and granulomatous inflammation. Undetected hypercalcemia and hypercalciuria can cause nephrocalcinosis, renal stones, and renal failure. Corticosteroids cause prompt reversal of the metabolic defect. Chloroquine, hydroxychloroqune, and ketoconazole are the drugs that should be used if the patient fails to respond or develops dangerous side effects to corticosteroid therapy.