Hypercalcemia and elevated serum calcitriol in a patient with seminoma.

This report describes a 49-year-old man with hypercalcemia and seminoma. His serum calcitriol (1,25-dihydroxy-vitamin D) level was markedly elevated. Additional endocrine evaluation revealed a normal serum phosphate level, hypercalciuria, and normal serum levels of immunoreactive parathyroid hormone. Serum calcium and calcitriol levels returned to normal following partial resection and successful combination chemotherapy. The association of hypercalcemia and elevated serum calcitriol levels has been previously described in a few patients with malignant lymphoma, but, to our knowledge, not in patients with solid tumors. The mechanism of hypercalcemia in this patient is not proved, but available evidence suggests calcitriol as the mediator.