Effect of serum 25-hydroxyvitamin D concentrations on skeletal mineralization in black and white women

Abstract

There is controversy over the adverse effect of vitamin D deficiency on bone mineralization. The purpose of this study was to determine the ethnical differences in vitamin D and bone mineralization as well as the association between vitamin D deficiency and bone mineralization defects. We examined serum 25-hydroxyvitamin D (25(OH)D) levels and transiliac bone biopsies in 92 healthy black and white women, aged 20-73 years. The major bone mineralization indices include osteoid volume per bone volume (OV/BV), osteoid surfaces per bone surface (OS/BS), osteoid thickness (O.Th) and mineralization lag time (Mlt). 25(OH)D levels were significantly lower and prevalence of 25(OH)D deficiency was significantly higher in blacks than in whites. However, none of the mineralization indices showed significant difference between the two groups. In addition, there was no significant correlation between 25(OH)D levels and mineralization indices in both black and white cohorts. Only one case had O.Th marginally greater than 12.5 µm, which is the cutoff value for identifying bone mineralization defects. OV/BV and OS/BS, but not O.Th, were significantly positively correlated with activation frequency (Ac.f). Our study indicated: (1) vitamin D deficiency is common, but bone mineralization is not impaired in black women, and (2) there are no significant correlations between serum 25(OH)D levels and bone mineralization indices, suggesting that vitamin D deficiency may not be an independent factor contributing to bone mineralization defects and osteomalacia.