Serum leptin is correlated to high turnover in osteoporosis

OBJECTIVE: Clinical data have suggested that obesity protects against osteoporosis. Leptin, mainly secreted by white adipose tissue, might be involved by mediating an effect on bone metabolism. This study was conducted to investigate a possible relationship of leptin and bone turn-over in postmenopausal women with osteoporosis. METHODS: We measured bone mineral density (BMD), serum leptin levels and markers of bone metabolism, including osteocalcin and cross-laps in 44 patients with osteoporosis. The main group consisted of 32 postmenopausal women. RESULTS: Mean serum leptin was 13.1 mu g/L and showed no statistically significant difference to the levels measured in a collective of normal persons adjusted for age and BMI. When related to serum cross-laps as markers of bone resorption, a positive correlation (p < 0.05) was observed, whereas no correlation with osteocalcin could be seen. CONCLUSIONS: A dual control of bone formation by leptin is assumed: This involves local mechanisms acting on osteoblasts and a central inhibitory effect on bone metabolism via a hypothalamic relay. Our data indicate that the net effect of circulating leptin may cause bone loss and is significantly related to high-turnover serum bone markers, at least in postmenopausal women with osteoporosis.