Vitamin D metabolites in normal subjects during one year. A longitudinal study.
The serum concentrations of 25-hydroxycholecalciferol (25OHD3), 25-hydroxyergocalciferol (25OHD2), 24,25-dihydroxyvitamin D (24,25(OH)2D), and 1,25-dihydroxyvitamin D (1,25(OH)2D) were measured in 10 normal subjects every 2 months for 1 year. Parallel seasonal variations were found in serum 25-hydroxycholecalciferol and 24,25-dihydroxyvitamin D reaching maximum values in June. Moreover, a highly significant correlation between changes in these two metabolites was observed (r = 0.89, P less than 0.001). On the other hand, the mean serum 1,25-dihydroxyvitamin D concentration remained constant throughout the year. Our data add further evidence to the tight regulatory mechanism of serum 1,25-dihydroxyvitamin D and the lack of regulatory mechanism of serum 24,25-dihydroxyvitamin D.
D015652:25-Hydroxyvitamin D 2; D000328:Adult; D002112:Calcifediol / Q000097:blood; D004872:Ergocalciferols / Q000031:analogs & derivatives / Q000097:blood; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D012016:Reference Values; D012621:Seasons; D014807:Vitamin D / Q000097:blood*
D004872:Ergocalciferols; D014807:Vitamin D; D015652:25-Hydroxyvitamin D 2; C003564:1,25-dihydroxyergocalciferol; C028140:24,25-dihydroxyvitamin D2; D002112:Calcifediol