Higher 25(OH)D2 Is Associated With Lower 25(OH)D3 and 1,25(OH)2D3

Context: Despite common use of supplemental vitamin D2 in clinical practice, the associations of serum vitamin D2 concentrations with other vitamin D metabolites and total vitamin D are unclear. Objective: The aim of the study was to measure vitamin D2 and D3 levels and examine their associations with each other and with total vitamin D. Design: We performed a cross-sectional analysis of 679 randomly selected participants from the Osteoporotic Fractures in Men Study. 25-Hydroxyvitamin D2 [25(OH)D2], 25(OH)D3, 1,25-dihydroxyvitamin D2 [1,25(OH)2D2], and 1,25(OH)2D3 were measured using liquid chromatography-tandem mass spectrometry and were summed to obtain total 25(OH)D and 1,25(OH)2D. Associations between all metabolites (D2, D3, and total levels) were examined using Wilcoxon rank-sum tests and Spearman correlations. Results: 25(OH)D2 and 1,25(OH)2D2 were detectable in 189 (27.8%) and 178 (26.2%) of the men, respectively. Higher 25(OH)D2 levels did not correlate with higher total 25(OH)D (r = 0.10; P = .1...