Paul R. Clayton
Fellow, Institute of Food, Brain and Behavior, Oxford, United Kingdom

Abstract

Age-related changes in levels of testosterone and the symptoms associated with these changes have created growing interest in testosterone replacement therapy (TRT). The epidemiology of the andropause is reviewed, together with the rationale, uses and limitations of classical TRT, and new developments in testosterone re-partitioning utilising a natural (food-derived) product

INTRODUCTION

Total testosterone concentrations decrease in men as part of the normal ageing process at a rate of 1% -2% per year after the age of 40 (1-4). This decrease varies considerably between individuals, and while the cause of declining testosterone is unclear, it is likely due to a combination of reduced hypothalamic gonadotropin releasing hormone outflow, alterations in androgenic negative feedback and decreased responsiveness of testicular tissue (5). This decline in testosterone is associated with decreased albumin and increased sex hormone-binding globulin (SHBG), resulting in higher levels of serum testosterone binding to SHBG and causing an additional decrease in free (bioavailable) testosterone (6). The adverse effects of low free testosterone are diverse, potentially serious and – once recognised – relatively easily addressed.

TESTOTERONE, AGEING AND HEALTH

While testosterone is a pluripotent hormone with a wide range of biological functions, the clinical significance of a low or low-normal testosterone level in men is incompletely understood (7). Notwithstanding, declining testosterone is frequently associated wit ...