Endocrine Abstracts

Objective: The beneficial effects of testosterone replacement therapy (TRT) in men with hypogonadism on the body composition and metabolic parametersare well-established, but the intimate mechanisms of these effects are not fully understood. Resistin is a small protein that is involved in the regulation of glucose metabolism and is considered to be key in the development of insulin resistance and to induce proinflammatory effects. We hypothesize that TRT has an impact on the adipokine profile that mediates its positive effects on the metabolism.

Design: The aim of this pilot study was to evaluate the effects of testosterone replacement therapy (TRT) on the circulating levels of serum resistin in the study population.

Methods: A total 40 men with obesity and idiopathic hypogonadotropic hypogonadism (defined as serum testosterone concentration <12 nmol/l). Testosterone replacement therapy (TRT) with Testosterone Undecanoate (Nebido) was performed at baseline and at week 6. Serum resistin concentration was determined at baseline and at week 18 by means of ELISA.

Results: Mean age ± s.d. of the study participants was 49.4 ± 10.1 years. 50% of the subjects had type 2 diabetes mellitus. Circulating resistin was negatively associated with serum HDL concentration (r = −0.258, P < 0.05), and positively with fat mass as measured by BIA (r = 0.370, P < 0.05). TRT has led to a statistically significant reduction in circulating serum resistin levels (8172 pg/ml vs 4816 pg/ml; paired-samples t-test P < 0.021). This association persisted even after adjustment with potential confounders.

Conclusions: TRT in obese men with idiopathic hypogonadotropic hypogonadism has led to a significant improvement of metabolic outcomes and body composition as well as to a significant reduction in serum resistin levels. As no such data on this association has been reported in the literature thus far, further prospective studies are required to elucidate this association.