Inverse correlation between serum leptin concentration and vertebral bone density in postmenopausal women

Although the protective effect of obesity on bone mass has been ascribed to high body fat content, this is still controversial. The present study of 215 postmenopausal Japanese women investigated whether circulating leptin concentration was correlated with per cent fat mass or age-adjusted bone mineral density (Z-score). In this study population, the mean circulating leptin concentration was 10.15 +/- 5.42 (range 1.7-29.6) ng/ml. Significant correlations were found between circulating leptin concentrations and per cent fat mass (r = 0.514, p < 0.0001) and Z-score (r = -0.516, p < 0.0001), confirming the existence of an inverse relationship between leptin concentration and postmenopausal bone density. By contrast, no significant correlation was found between per cent abdominal fat mass and vertebral bone mineral density (r = -0.071). Serum leptin concentration reflects fat mass and postmenopausal bone mass in human subjects. Increased serum leptin levels might cause bone loss in postmenopausal Japanese women, and our results do not support the hypothesis that leptin induces or mediates the bone-protective effects of obesity.