A 45-year-old woman comes to the physician due to 1 year history of progressive shortness of breath and nonproductive cough. She has had no fever or weight loss. Her medial history is unremarkable. Her blood pressure is 124/84 mmHg, pulse is 76/min and respirations are 16/min. She has never smoked cigarettes. Crackles are heard in both mid lung zones on auscultation. The rest of the exam shows no abnormalities. Her serum calcium is increased. Angiotensin-converting enzyme (ACE) level is 105 ug/L (N:<40 ug/L). A radiograph of the chest shows bilateral hilar fullness. Which of the following is most likely the cause of this patient’s hypercalcemia?
B) Exogenous PTH production
C) Lytic bone lesions and increased IL-6 production
D) Granulomatous secretion of PTH-related hormone
E) Increased production of 1,25-dihydroxycholecalciferol
The correct answer is E. This patient most likely has Sarcoidosis, a disease of granulomatous inflammation characterized by hilar lymphadenopathy, pulmonary reticular opacities and inflammation of other tissues, such as skin, eyes, joints, heart, and GI tract. Approximately 10-20% of patients who have sarcoidosis will have clinical or laboratory evidence of hypercalcemia. Granulomatous disease causes hypercalcemia via increased production of calcitriol, also known as 1,25-dihydoxycholecalciferol, the active version of vitamin D.