Vitamin D 3 (1, 25 D ihydroxyvitamin D 3)

Vitamin D₃ (1,25-Dihydroxyvitamin D₃), also known as Calcitriol, is the biologically active form of vitamin D produced in the kidneys from 25-hydroxyvitamin D. This test evaluates disorders related to calcium and phosphorus metabolism, parathyroid hormone abnormalities, kidney disease, and certain granulomatous disorders such as sarcoidosis and tuberculosis. Unlike the 25-hydroxyvitamin D test, this assay is not used for routine vitamin D deficiency screening but is specifically indicated in cases of renal disease, hypercalcemia, hypocalcemia, and suspected vitamin D metabolism disorders.