Associations of Serum Osteocalcin and Polymorphisms of the Osteocalcin Gene with Bone Mineral Density in Postmenopausal and Elderly Chinese Women

Background: The aims of this study were: (1) to evaluate the association of serum osteocalcin with bone mineral density (BMD) and markers of bone metabolism in postmenopausal and elderly Chinese women, and (2) to observe the relationships of single-nucleotide polymorphisms (SNPs) in and around the osteocalcin gene with osteocalcin and BMD.

Methods: A cross-sectional study was conducted with 725 postmenopausal Chinese women. Five SNPs (rs1543294, rs1800247, rs759330, rs2842880, and rs933489) of the osteocalcin gene were genotyped. Serum osteocalcin and intact parathyroid hormone (PTH), 25-hydroxyvitamin D [25(OH)D], and type I collagen containing cross-linked C-telopeptide (β-CTX) were measured. The BMD of the lumbar spine and proximal femur was measured by dual-energy X-ray absorptiometry.

Results: Osteocalcin was positively correlated with serum phosphorus (p = 0.001), alkaline phosphatase (ALP; p < 0.001), PTH (p = 0.002) and β-CTX (p < 0.001), and negatively correlated with BMD at the lumbar spine (p < 0.001) and total hip (p = 0.002). No significant association was obtained between the SNPs, haplotypes of the osteocalcin gene, and BMD or osteocalcin.

Conclusion: Our results suggest that osteocalcin was positively correlated with serum phosphorus, ALP, PTH, and β-CTX, but negatively correlated with BMD at the lumbar spine and total hip. Common genetic variants of the osteocalcin gene may not be a major contributor to variations in serum osteocalcin or BMD in postmenopausal and elderly Chinese women.