Hypercalcemia associated with increased circulating 1,25 dihydroxyvitamin D in a patient with pulmonary tuberculosis.

Studies are described in a 53-year-old man with far-advanced pulmonary tuberculosis who developed transient increases in circulating 1,25 dihydroxyvitamin D (1,25(OH)2D) and hypercalcemia while on antituberculous treatment. Serial dilution of an extract of the patient's serum obtained while he was hypercalcemic displaced [3H]-1,25(OH)2D3 from chick intestinal receptor in a manner identical to authentic 1,25(OH)2D3. Serum 25-hydroxyvitamin D (25OHD) was suppressed during the abnormal elevation of serum 1,25(OH)2D. It is concluded that tuberculosis is another chronic granulomatous disease in which hypercalcemia may result from abnormal metabolism of vitamin D.