Vitamin D binding Protein (VDBP)

This assay is an enzyme immunoassay intended for thequantitative determination of free and not actin complex bound vitamin Dbinding protein in serum, plasma and urine. For in vitrodiagnostic use only.VitaminD binding protein (VDBP, also known as group-specific component / Gc pro­tein)is a multifunctional serum protein which is formed in the liver. High estrogenlevels, caused e. g. by pregnancy or hormonal birth control, stimulate itssynthesis. VDBP can be found in plasma, ascites, liquor, urine and at thesurface of various cell types. Inthe blood, VDBP binds the bigger part of the circulating 25-OH vitamin D andbrings it to the kidneys, where it is transformed into the hormone 1,25-(OH)2vitamin D. Inaddition, VDBP binds monomeric actin at the ratio of 1:1. Actin is anintracellu­lar protein which is available as monomer or filament. Massivetissue destruction or cell death cause the plasma level of actin to risesignificantly, whereupon VDBP-actin complexes are formed which are removedquickly. Hence the VDBP level of trauma or sepsis patients decreases quickly,especially in patients with a high level of multi-organ failure. Furthermore VDBPis a precursor of the immunomodulating protein Gc-MAF (Gc protein-derivedmacrophage activating factor) which increases the activity of macrophagesagainst tumours. Indications-Prognostic factor for trauma patients- Nephritic syndrome-Tumours