Endocrine Abstracts

There are a number of endocrine changes which occur during the aging process, including changes in the growth hormone – IGF1 axis, a fall in DHEAS levels, changes in the renin-angiotensin system, and alterations in the hypothalamo-pituitary gonadal axis. Testosterone levels decline with age, with an average decrease in testosterone levels of approximately 1.5% per year. The prevalence of subphysiological testosterone levels is approximately 20% by the age of 50 and 50% by the age of 80. Manifestations of low testosterone include sarcopenia, falls in bone mineral density, increased fat mass, central obesity, insulin resistance, decreased libido and energy, irritability and grumpiness, and dysphoria. Subtle falls in testosterone levels begin after the age of 30, in particular with falls in free testosterone levels as a consequence of a rise in SHBG. Many of the features of hypogonadism mimic those of adult GH deficiency, reducing the specificity of the use of a symptom score for diagnosis. In a recent prospective studies of male patients recruited on the basis of ‘suggestive symptoms’ and testosterone levels within the lower end of the reference range, a double blind placebo controlled study of the effects of three doses of oral testosterone undecanoate (80, 160, 240 mg ‘Testocaps’)was conducted to determine whether testosterone administration conferred any benefits in terms of symptoms (1ary study objective) and body composition (strength, fat mass and muscle composition). None of the testosterone doses used was associated with a significant change in symptomatology, although the higher doses of testosterone were associated with increased lean body mass and bone density. We concluded that testosterone replacement was not indicated in such males; the impact of insulin resistance and cardiovascular risk factor reduction by testosterone therapy was not addressed in this study.