About 90% of the total circulating 25OH Vitamin D is bound to the so-called VDBP or DBP. The remaining 10% are bound to albumin, the main protein of human blood plasma.
A tiny fraction representing 0.04% of the total 25OH Vitamin D concentration circulates as a free form. This fraction of free 25OH Vitamin D relates to the biological activity of Vitamin D, and therefore may better reflect the physiological action of Vitamin D than the total concentration of 25OH Vitamin D.
The DiaSource Elisa assays is based on the use of proprietary anti-25OH D2/D3 monoclonal antibody and offers a direct method for measuring Free 25OH Vitamin D in human serum samples. Clinical studies have been indicating that the measurement of free 25OH Vitamin D in serum samples of e.g., pregnant women, haemodialysis patients, CDK-patients and patients with liver failure provides more relevant diagnostic information than measurement of routine Total 25OH Vitamin D assays.
You can find all our Vitamin D products and Free Vitamin D products in our RIA /ELISA /or in our Antibodies & Antigens catalogues.
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