25-OH Vitamin D ELISA kits are assays designed to detect 25-hydroxyvitamin D, also known as calcifediol. A prehormone produced in the liver, it is converted in the kidneys to calcitriol, the active form of vitamin D. It is a stable vitamin D metabolite and, together with 25(OH)D2 (ercalcifediol), is used to measure the concentration of the vitamin D the body. Vitamin D deficiencies can be detected through such testing. Higher levels of 25-OH D at early breast cancer diagnosis have been linked to lower tumor size and better survival. Visit the supplier page for more information about detection range and reactivity.