Recent studies suggest that the concentration and genotype of Vitamin D binding protein (DBP) are important factors that determine the bioavailability of 25OH Vitamin D in blood. There is accumulating data that for instance in pregnant women, chronic kidney disease, liver failure, bladder cancer and pancreatic cancer, or in hemodialysis patients the measurement of free 25OH Vitamin D in serum provides more relevant diagnostic information than total 25OH Vitamin D.

Several research groups have therefore called for a direct measurement of free 25OH Vitamin D, instead of using inaccurate calculation methods….Read More