Influence of gender, age and renal function on plasma adiponectin level: the Tanno and Sobetsu study.

DESIGN The aim of this study was to determine the association between aging and adiponectin level from the aspect of the influence of renal function and sex hormones in humans. METHODS Serum adiponectin and blood urea nitrogen (BUN) levels were measured in 964 subjects (372 males) aged 60.3+/-12.5 years. Testosterone and free testosterone levels were measured in 123 males, and estrone and estradiol levels were measured in 114 females. The subjects were divided into two age groups; 65 years of age or older (Age > or = 65 group) and less than 65 years of age (Age < 65 group). RESULTS Adiponectin level increased linearly with aging in males, whereas it increased dramatically in females until their 50s. The patterns of changes in adiponectin were similar to those in BUN. In multiple- regression analysis using adiponectin as a dependent variable BUN was selected as a significant independent variable in all subjects and in subjects in the Age > or = 65 group, whereas bioactive sex hormones were not selected. CONCLUSIONS A decrease in adiponectin clearance in the kidney may be the cause of high levels of adiponectin in the elderly. Adiponectin level seems to be influenced more strongly by BUN than by sex hormones and to be increased by a decline in renal function with aging.