1,25-Di Hydroxy Cholecalciferol

This test measures the level of 1,25-Di Hydroxy Cholecalciferol (the biologically active form of Vitamin D) in the blood. 1,25-Dihydroxy vitamin D plays a primary role in the maintenance of calcium homeostasis. A part of circulating 25-hydroxy vitamin D is converted to 1, 25-dihydroxy form in the kidneys. Patients who present with hypercalcemia, hyperphosphatemia and low PTH may suffer from the unregulated conversion of vitamin D from mono-hydroxy to dihydroxy form as is seen in granulomatous diseases like Sarcoidosis and nutritionally induced Hypervitaminosis D.