Leptin and Bone Mineral Density in Healthy Postmenopausal Iranian Women: A Population-based Study

Obesity is associated with both higher bone mineral density (BMD) and plasma leptin con-centration. Inconsistent data are available about the relationship of leptin concentration and BMD, and the aim of this study was to explore the relationship of plasma leptin concentration with BMD as well as bone-related markers in healthy postmenopausal Iranian women. Two-hundred and ninety-six postmenopausal women from a popu-lation-based study on prevalence of osteoporosis in Shiraz participated in this study. The BMD was determined at the lumbar spine (L1-L4) and neck of femur by dual-energy X-ray absorpti-ometry. Blood samples were taken in the fasting state for plasma leptin, serum parathyroid hor-mone, creatinin, calcium, albumin, phosphorus and alkaline phosphatase evaluations. The mean age of the participants was 60.75±7.46 years and the mean body mass index (BMI) was 27.51±5.3 kg/m2. Mean leptin concen-tration was 18.12±9.08 ng/ml. One-hundred and forty-two (48%) individuals were osteoporotic, with mean plasma leptin concentration being significantly lower in these individuals (P<0.0001). BMDs at both the lumbar spine (r=0.25; P<0.0001) and the neck of femur (r=0.29; P<0.0001) had significant positive correlation with plasma leptin. The association between BMD and plasma leptin concentration was no longer significant when adjusted for BMI. There was no correlation between plasma leptin con-centration and bone-related markers. This cross-sectional study suggests that the relationship of plasma leptin concentra-tion with BMD is mediated through obesity and plasma leptin is dependently associated with BMD.