Sarcoidosis, also called sarcoid, is a disease involving abnormal collections of inflammatory cells (granulomas) that can form as nodules in multiple organs. The granulomas are most often located in the lungs or its associated lymph nodes, but any organ can be affected. Sarcoidosis seems to be caused by an immune reaction to an infection or some other trigger (called an antigen) that continues even after the initial infection or other antigen is cleared from the body. In most cases it clears up by itself without any medical intervention, but some cases go on to affect the person long-term or become life-threatening and require medical intervention, most often with medications. Elevated calcitriol is the main cause for high blood calcium in sarcoidosis and is overproduced by sarcoid granulomata. Gamma-interferon produced by activated lymphocytes and macrophages plays a major role in the synthesis of calcitriol.