Relation of body mass index to vitamin D, PTH, and bone turnover markers levels among women in Shanghai area

Objective To examine the relationship of body mass index (BMI) with levels of vitamin D,parathyroid hormone (PTH),and bone turnover markers among women in Shanghai area.Methods Altogether 810 Chinese women aged 45 year and older were enrolled to study the associations by multiple linear regression analyses.Bone mineral density was measured by a dual energy X-ray absorptiometry (Lunar,Prodigy,GE),Serum 25-hydroxyvitamin D [25 (OH) D],PTH,C-telopeptide of type Ⅰ collagen (CTX),osteocalcin (BGP),and bonespecific alkaline phosphatase (BSALP) were measured.Results (1) 25 (OH) D,BGP,BSALP,and CTX levels were significantly lower in obesity group than in control group ; PTH level was significantly higher in obesity group than in control group.(2) In multiple linear regression analyses,BMI was significantly associated with lower 25 (OH) D (β =-0.017,P =0.006),BGP (β =-0.077,P =0.019),and higher PTH (β =0.025,P =0.000).Conclusions (1) There were siginificant associations between higher BMI and lower 25 (OH) D among women in Shanghai.(2) Serum osteocalcin was associated not only with bone metabolism but also with energy metabolism. Key words: 25-hydroxyvitamin D;  Parathyroid hormone;  Body mass index;  Osteocalcin