Synonyms: Cholecalciferol Metabolite; 25-Hydroxycalciferol; 25-OH-D; Vitamin D3 Metabolite

Why It Is Done

Determine if a patient has a deficiency or excess of vitamin D.

Test Overview

25 hydroxy vitamin D is the most accurate measure of vitamin D stores in the body.

25 hydroxy vitamin D is stored in the liver where it is converted from other forms of vitamin D, either obtained from the diet or made in the skin by sunlight.

25 hydroxy vitamin D is then changed to its active form, 1,25 dihydroxy vitamin D in the kidney. This active form of vitamin D causes increases in calcium and phosphate by activity primarily on the intestines, kidney and bone.

How To Prepare

No special preparation needed.