The influence of serum leptin concentration on bone mass assessed by quantitative ultrasonometry in pre and postmenopausal women.

Objective: the aim of this study was to evaluate the influence of serum leptin concentration on bone mass assessed by quantitative ultrasound (QUS) in a large sample of healthy pre and postmenopausal women.
Design: 555 healthy pre and postmenopausal (n=261 and n=294) women (mean age, 49.5+/-17.2 years) not on hormone replacement therapy were recruited on the occasion of a routine gynecological visit. Before entry to the study, all women had answered a detailed questionnaire on important risk factors and gave written informed consent. Speed of sound (SOS), broadband ultrasound attenuation (BUA) and stiffness index (SI) of the os Calcis were measured using the Achilles ultrasonometer (GE/lunar). We systematically investigated the relation of menopause, BMI and leptin on bone mass by allocating women into the following groups: (a) premenopausal women BMI<25 kg/m(2) (N=178); (b) premenopausal women BMI>25 kg/m(2) (N=83); (c) postmenopausal women BMI<25 kg/m(2) (N=125); and (d) postmenopausal women BMI>25 kg/m(2) (N=169). Additionally we investigated the relation of serum leptin concentrations, age and BMI on ultrasonometry variables by performing a multiple linear regression analyses.
Results: in the initial analyses premenopausal women showed a significantly (P<0.001) lower mean age, weight, BMI, follicle stimulating hormone (FSH) and leptin concentration, a higher mean height, serum estradiol and ultrasonometry variables in comparison to postmenopausal women. Irrespective of the menopausal status, women with a BMI>25 kg/m(2) had significantly higher leptin concentrations (P<0.001) and BUA (P<0.05) whereas SOS and SI was not significant different, compared to women with a BMI<25 kg/m(2). The multiple linear regression analyses showed that only BMI but not Leptin was related to higher ultrasonometry variables, whereas increasing age was associated with a decrease in ultrasonometry variables. Furthermore, the multiple linear regression analyses confirmed that age and BMI were the only statistically significant independent predictor for ultrasonometry variables. There was no significant influence of leptin on ultrasonometry variables even after controlling for BMI or age, or BMI and age.
Conclusions: serum leptin concentrations are significantly higher in pre and postmenopausal obese women, compared with normal weight controls. Ultrasonometry variables are influenced by age and BMI but not by serum leptin concentrations.