The value of testosterone replacement therapy (TRT) for older men is currently a topic of intense debate, and in a recent review study entitled “Injection of Testosterone May Be Safer and More Effective than Transdermal Administration for Combatting Loss of Muscle and Bone in Older Men,” researchers at the University of Florida compared the modes of delivery and concluded that intramuscular injection of TRT offered greater health benefits and lower cardiovascular risks than transdermal administration by skin patch or gel. The study is published in the American Journal of Physiology—Endocrinology and Metabolism.
The Endocrine Society recommends TRT for men with androgen deficiency, defined as low serum T with consistent symptoms and signs of hypogonadism, including decreased sexual function, loss of axillary and pubic hair, low bone mineral density, loss of motivation, mood or concentration and loss of muscle strength and work capacity. TRT is most frequently administered by intramuscular (i.m.) injection of long-acting T esters or transdermally via patch or gel preparations and infrequently via oral administration. The treatment is beneficial in hypogonadal men, allowing them to develop increased muscle mass and strength, decreased fat mass, increased bone mineral density and improved sexual function.
However, TRT also carries known risks including development of polycythemia (hematocrit >50) in 6% of those treated, decrease in HDL, breast tenderness and enlargement, prostate enlargement, increase in serum PSA and prostate-related events and may cause suppression of the hypothalamic-pituitary-gonadal axis. Nevertheless, TRT does not increase the risk of prostate cancer, with putative risks including edema and worsening of sleep apnea. Several reports have also indicated that TRT may produce cardiovascular (CV) risks, while others report no risk or even benefit.
However, based on the reviewed studies, the researchers indicate there are advantages in administering TRT by injection, rather than transdermally or orally for the treatment of older hypogonadal men.
The authors also indicate that many studies determined that the combination of i.m. T plus finasteride produces musculoskeletal benefits without the prostate enlargement that results from T alone. Furthermore, according to the team, finasteride produces fewer side effects and may also produce cardiovascular benefits and/or reduce prostate cancer by reducing dihydrotestosterone (DHT).
In the review, the authors conclude that although more research is necessary, i.m. injected T plus finasteride may be both safer and more effective in the treatment of older hypogonadal men.