Endocrine Abstracts

Introduction: There is increasing evidence suggesting that adiponectin plays a role in the regulation of bone metabolism. We have studied the changes in the circulating concentration of adiponectin in lean and obese post-menopausal women with and without osteoporosis and its association with a marker of bone formation – type 1 procollagen amino-terminal pro-peptide (P1NP) and a marker of bone resorption – type 1 collagen C-telopeptide (βCTX).

Methods: Venous blood samples were obtained from 37 non-osteoporotic and 34 osteoporotic post-menopausal women who had been fasted. All subjects had bone mineral density (BMD) measured as part of an osteoporosis screening program. Total- and high molecular weight (HMW) adiponectin and osteoprotegerin (OPG) were measured by ELISAs; βCTX and P1NP by ECLIA. The relationship between total and HMW-adiponectin, body mass index (BMI), BMD, OPG, βCTX and P1NP was investigated.

Results: We observed a positive correlation between BMI and BMD (r=0.44, P<0.001). There was no difference in the circulating adiponectin concentration in those with or without osteoporosis. However, when stratified for BMI the concentration was lower in obese compared to lean subjects but a statistically significant difference was only observed in the HMW/Total adiponectin ratio with lean patients without osteoporosis having a higher ratio when compared to their obese counterparts (P<0.05). There were significant negative correlations between HMW-adiponectin and HMW/Total adiponectin ratio with BMI (r=−0.25, P=0.040 and r=−0.27, P=0.030 respectively) and between HWM/Total adiponectin ratio with OPG (r=−0.44, P<0.001).

Conclusions: Our data suggest that there is no significant difference in the circulating concentration of fasting early morning adiponectin in post-menopausal women with or without osteoporosis. The correlation between HMW/Total adiponectin ratio and OPG may indicate that adiponectin could influence bone metabolism by altering osteoblast production of OPG thereby affecting osteoclast mediated bone resorption.