DescriptionVitamin D 1, 25 Dihydroxy test measures the levels of the active form of vitamin D, which is 1, 25 Dihydroxycholecalciferol, in the body. Vitamin D 1, 25 Dihydroxy is also known as calcitriol. This test is ordered when investigating a problem related to bone metabolism or parathyroid function and possible Vitamin D deficiency or malabsorption. Show Less