The Calcium Conundrum: Hypercalcemia of Unknown Etiology

Hypercalcemia is a common clinical finding with a wide variety of clinical presentations and etiologies. The differential is broad and includes hyperparathyroidism, malignancy, medication adverse effects, endocrinopathies, and a variety of granulomatous diseases. We present the case of an 84-year-old woman with severe parathyroid hormone-independent hypercalcemia and elevated 1,25-OH Vitamin D. Non-necrotizing granulomas were identified on bone marrow biopsy. After an exhaustive workup for granulomatous disease, the patient was felt to have sarcoidosis isolated to the bone marrow and started on prednisone to suppress 1-alpha hydroxylase activity.