Hypercalcemia due to giant cell myocarditis: a case report

Granulomatous diseases are a rare cause of hypercalcemia. The pathogenesis is presumed to be from endogenous production of 1,25-dihydroxyvitamin D by activated macrophages in granulomatous lesions, which harbor the 1 alpha-hydroxylase enzyme. Herein the first case of hypercalcemia associated with giant cell myocarditis, an unusual type of granulomatous process, is reported. In this case, a patient with giant cell myocarditis had development of progressive heart failure and cardiorenal syndrome that required biventricular support. One year later, hypercalcemia associated with a relatively high 1,25-vitamin D level and a concomitantly suppressed parathyroid hormone level developed in the presence of stage 4 chronic kidney disease. Her other workup of hypercalcemia was unrevealing for vitamin D intoxication and multiple myeloma. Computed tomography of her chest showed no signs of hilar lymphadenopathy. Her calcium levels returned to normal with low-dose steroid therapy and have remained normal following a successful heart transplant. This case illustrates an unusual cause of hypercalcemia thought to be due to extrarenal calcitriol production associated with giant cell myocarditis. (C)2013 NATCO, The Organization for Transplant Professionals