Vitamin D Binding Protein (DBP), Free Calcidiol, and Total Calcitriol in Adults from Northern Greece

Background: An ongoing debate has been raised on whether is better to use total or free calcidiol as a screening test in the population. Methods: In winter and summer, free calcidiol, total calcitriol, and vitamin D binding protein (DBP) concentrations were determined by immunoenzymatic assays in ۳۲۶ adults (۱۶۱ males, ۱۶۵ females). These included ۹۹ osteoporotic patients, ۵۳ type ۱ and ۵۱ type ۲ diabetics, and ۱۲۳ athletic healthy persons, all from northern Greece. Results: In the whole sample, free calcidiol mean concentrations differed significantly (p < ۰.۰۰۱) between males (۵.۵۳ pg/ml) and females (۴.۶۸ pg/ml). Free calcidiol was significantly greater in the athletic healthy group (۶.۰۲ pg/ml) than in the three patient groups, and lowest in the osteoporosis group (۳.۶۹ pg/ml). Total calcitriol mean concentration did not differ significantly between genders in the whole sample (p = ۰.۸۹۶) or in the study groups, except for type ۲ diabetics (males ۳۸.۳۳ pg/ml, females ۵۴.۵۲ pg/ml, p = ۰.۰۰۱). It was significantly less in the osteoporotics (۳۴.۶۱ pg/ml) than in the athletic healthy group (۴۱.۶۵ pg/ml, p = ۰.۰۳۷) and type ۱ diabetics (۴۳.۷۳ pg/ml, p = ۰.۰۳۰), whereas it did not differ significantly between the other study groups. The DBP mean concentrations were not significantly different between genders in the whole sample and the study groups nor among the study groups (p = ۰.۴۶۷). Conclusions: Comparisons with our previously reported results of total calcidiol suggest the measurement of free calcidiol offers nothing more than that, and total calcitriol is not a sensitive measure for assessing vitamin D status.

Keywords:

Calcidiol , Calcitriol , Vitamin D , Vitamin D Binding Protein.