The current indication for TRT is hypogonadism, a syndrome complex combining hypogonadal symptoms and low testosterone concentrations. The optimal formulation for the treatment of hypogonadism is one that generates a physiological testosterone concentration in the age adjusted reference range, as well as the concentration of its metabolites oestradiol and dihydrotestosterone, while ideally mimicking the circadian rhythm in younger subjects. Optimal treatment should lead to correction of sexual malfunction, improvement in body composition, including increased muscle mass, endurance and strength, loss of excess fat mass, improvement in bone density, increased secondary sexual hair and shaving frequency, and correction of anaemia. Concomitant with these changes, improvement in insulin sensitivity should occur with some regression of the features of the metabolic syndrome. The ideal preparation should be convenient to administer, with both patient acceptability and tolerability, be inexpensive, and devoid of adverse effects. Such potential adverse effects of over-replacement of testosterone include polycythaemia, reduction in HDL, and potential stimulation of prostatic growth. The range of products available in the UK is growing: oral, transdermal, intramuscular and implants are readily available; selection can thus be tailored to individual patient needs. Each has its advantages and disadvantages, and there is no one type suits all' preparation. Moreover, it is evident that the response to TRT also depends on individual pharmacogenomic considerations; in particular, patients with short CAG repeats in the androgen receptor are relatively more sensitive to TRT, and may require lower doses. Selective androgen receptor modulators are in development but their precise role in TRT remains to be determined.
Declaration of interest: Conflict of Interest: PMB has receoved occsional honoraria from Bayer Schering for lecturing on the uses of Testogel in LOH.
Funding: No specific grant from any funding agency in the public, commercial or not-for-profit sector.