The rationale for the prescription of calcium and vitamin D to a person with sarcoidosis is unclear. Hypercalcemia, a high calcium level in the blood, is common with sarcoidosis due to the uncontrolled synthesis of vitamin D causing increased absorption of calcium by the intestine. Both hypercalcemia and hypercalciuria, abnormal amounts of calcium in the urine, pose significant threats to an individual and are considered complications of sarcoidosis. Calcium and vitamin D are conventional treatment for bone thinning, called osteoporosis, but with the risk of increased calcium in blood and urine of people with sarcoidosis, they should not be used to treat osteoporosis. There are other medicines, for example Fosamax® (alendronate), for the treatment of osteoporosis that do not depend upon alteration of calcium metabolism.
Given the above, you should ask your doctor why he has asked you to take calcium and vitamin D, when you have sarcoidosis, a disease complicated by high levels of both.