Oral Presentation Australian & New Zealand Obesity Society 2014 Annual Scientific Meeting

Sex hormones, body composition and cardiometabolic health (#29)

Bu B Yeap 1 2
  1. School of Medicine, University of Western Australia, Perth, WA, Australia
  2. Department of Endocrinology and Diabetes, Fremantle Hospital, Fremantle, WA, Australia

Testosterone concentrations are lower in older compared to younger men, and ageing is accompanied by an increasing prevalence of ill-health. There is ongoing debate whether changes in sex hormones are biomarkers or causal contributors to disease in ageing men. In this context the role of the testosterone metabolites dihydrotestosterone, a more potent androgen, and estradiol, a ligand for the estrogen receptor, remains unclear. Observational studies document associations of lower testosterone concentrations with higher body mass index, insulin resistance and diabetes risk. The relationship may be bidirectional, with reduced testosterone exposure contributing to adiposity and diabetes risk, while central obesity and insulin resistance impair endogenous testosterone production. Lower concentrations of testosterone or dihydrotestosterone, rather than estradiol, are associated with cardiovascular disease. Of note, in older men survival is predicted by optimal rather than high testosterone concentrations. Therefore, lower circulating androgens in men are robust biomarkers for poorer health outcomes. Testosterone therapy results in increased lean mass, higher bone mineral density and reduced fat mass in men with low-normal baseline concentrations. In men estradiol plays a major role in bone health. In addition, there is emerging evidence indicating that aromatisation of testosterone to estradiol regulates accumulation of subcutaneous and intraabdominal fat. However, completed randomised clinical trials of testosterone in men have not been powered for clinical outcomes related to incident diabetes or cardiovascular disease. Large scale randomised clinical trials are needed to clarify the utility of hormonal interventions to preserve health in the increasing population of ageing men. Pending such studies, middle-aged and older men should be encouraged to engage in healthy lifestyle behaviours, to preserve endogenous testosterone production as well as improve health outcomes.