Aging-related decline of gonadal function in healthy men: Correlation withbody composition and lipoproteins

OBJECTIVE: To assess if androgen decline in physiological aging contributes to the concomitant changes in body composition and lipoprotein levels. DESIGN: Cross-sectional, observational study. SETTING: A university-based outpatient center. SUBJECTS: The study comprised 206 healthy volunteers (aged 18-95 years). MEASUREMENTS: Blood samples were drawn after an overnight fast for the assa y of hormones (free testosterone (FT), estradiol (E-2), and sex hormone-bin ding globulin (SHBG)) and lipids (total cholesterol, triglycerides, high-de nsity lipoprotein cholesterol, and lipoprotein Lp(a)). At the same time, bo dy composition was assessed by both anthropometry (fat mass percentage (FM% ) estimated from four measures of skinfold thickness using the Durnin and W omersley equation and the Siri equation) and by bioimpedance analysis (FM% estimated using the Segal or Deurenberg equations, respectively, for subjec ts younger or older than 62 years). RESULTS: A significant age-related decline was found for FT and E-2 concent rations, whereas SHBG levels were related positively with age. No significa nt association was apparent between hormonal changes and the concomitant mo difications of body composition and lipoproteins. Only SHBG showed a signif icant inverse association between FM% and the waist-to-hip ratio, independe nt of age. The comparison between older hypogonadal (with FT levels below t he lower limit of the normality range assessed in younger subjects) and eug onadal men did not show any significant differences in body composition or lipid profile. CONCLUSIONS: This study suggests that, in men, androgen decline caused by n ormal aging does not significantly affect some targets of testosterone acti on, such as body composition and lipid metabolism. Therefore, androgen supp lementation in hypogonadal older men cannot be expected to influence nutrit ional status and body composition to the same extent that it does other mai n targets of testosterone action, such as sexual activity and muscle streng th. However, we cannot exclude that selected subsets of older patients with low testosterone levels, especially if affected by catabolic disease, coul d benefit from the effects of androgen administration on nutritional status .