Vitamin D receptor genotype BB is associated with higher serum osteocalcin in first pregnancy.

Aim: Serum osteocalcin was shown in a previous study on first trimester pregnant women to correlate with bone density and to distinguish between fast and slow bone losers. The objective of the present study is to examine whether serum osteocalcin is related to vitamin D receptor (VDR) BsmI polymorphism in pregnant women.

Study Design: We determined osteocalcin serum levels and VDR BsmI genotype in 97 healthy first trimester pregnant women consecutively recruited during six months.

Results: BB (21%), Bb (38%) and bb (41%) genotypes showed similar osteocalcin serum levels. However, in primigravidas (n=38) the BB genotype was significantly associated with higher mean osteocalcin level (9.67 ng/mL) than the Bb (8.07 ng/mL) and the bb genotype (8.14 ng/mL), respectively (P<0.05). The VDR genotype was the only independent parameter to correlate with serum osteocalcin (P<0.05).

Conclusion: Only primigravidas show in the first trimester a relation between the bone formation parameter serum osteocalcin and the VDR genotype BB which indicates a higher risk of fractures. For further clinical applications serum osteocalcin and VDR genotype should be tested on a cohort of primigravidas including measurements of bone density.