Estrogen replacement therapy is frequently a topic of discussion for women during and after menopause. There are a number of benefits, such as preserved bone density in the spine (helping to prevent osteoporosis), as well as drawbacks including hypercoagulability (increased susceptibility to clotting) with such therapy. However, testosterone replacement for men is not as frequently discussed. Perhaps, the reason for this stems from the fact that symptoms of menopause and decreased estrogen present more suddenly whereas the decline in testosterone is rather progressive. According to Baer et al., testosterone decline begins in men after age 30 and continues at an annual rate of 0.2% to 1.0%.
So what are some of the implications of testosterone deficiency, or late-onset hypogonadism? Baer et al. lists a few of these, including induced frailty, sarcopenia (muscle wasting), poor muscle quality, muscle weakness, hypertrophy of adipose tissue, and impaired neurotransmission. Decreased libido is also another side effect often discussed.
In light of this, it seems somewhat curious as to why testosterone replacement is not more frequently prescribed. As alluded to by Bhattacharya et al., this may be because of the relatively unknown long-term effects of testosterone replacement therapy; especially in consideration with prostate cancer and perhaps other cancers as well.
There are some other concerns as well with prescribing testosterone. It is a performance enhancing drug and is also being increasingly consumed by middle-aged men to get an "edge". Thus, there needs to be further research to evaluate whether testosterone replacement should be given to men who may be suffering from symptoms of natural reductions in the steroid over time, and also whether it is appropriate to prescribe testosterone simply for providing an "edge."
There seems to be a growing interest in the subject as it may significantly impact the millions of patients with hypogonadism that are currently not receiving replacement therapy and because of the increased media coverage of businessmen taking testosterone to augment their business performance. However, it will take a considerable amount of time to find out the long-term effects as well as the "optimal" values that should be sought for men of different ages to create clinically relevant benefits without creating possible harms.