Hypercalcemia-induced acute kidney injury in a Caucasian female due to radiographically silent systemic sarcoidosis.

. Sarcoidosis is a rare autoimmune disease resulting in formation of non-necrotizing "non-caseating" granulomas generally in the lung. The disease classically strikes African American females in their fourth and fifth decades. The resulting hypercalcemia is a result of 1-α hydroxylase overexpression in granulomas with increased 1,25-dihydroxy vitamin D levels. This phenomenon can also be observed in mycobacterial and fungal infections that produce granulomas in infected patients. Thus, chronic infectious diseases are part of differential diagnosis of granulomatous processes. We present an elderly Caucasian female who presented with hypercalcemia with serum calcium of 11 - 14 mg/dL and an elevated ionized calcium of 1.4 - 1.5 mmol/L. Initially cholecalciferol supplements were stopped, but hypercalcemia persisted for more than 2 months. 1,25-dihydroxy vitamin D levels were markedly elevated with low normal 25-hydroxy vitamin D levels, angiotensin-converting enzyme levels were also high, and chest computed tomography (CT) imaging was negative for any lymphadenopathy (including perihilar lymphadenopathy). Malignancy and infectious workups were negative for fungal and mycobacterial infections. Positron emission tomography revealed several small lymph nodes in right upper lobe of lung, and biopsy of bone marrow and lung lymph-nodes revealed non-caseating granulomata. We present an atypical case of occult sarcoidosis presenting mainly with biochemical findings without any definitive imaging findings, making diagnosis a clinical challenge.