Lower testosterone in older men may be a positive benefit because the body of an older man may not be able to withstand the abuse that a younger, more aggressive man with higher testosterone levels could handle. According to the American Association of Clinical Endocrinologists, “…as many as 30 percent of men older than 75 have a testosterone level that’s below the normal range of testosterone in younger men. Whether treatment is necessary remains a matter of debate. Science has not proven that TRT for age-related testosterone decline is of any medical value. Yet, the pharmaceutical companies have turned an age-related hormone decline into a disease.”
5) Progesterone . Hey, men need progesterone too - or at least they need adequate levels. See this link on Progesterone and Men , but progesterone can help men out in many key areas and one of them is bone mass. I see very differing opinions on just how to raise progesterone. Some experts say you should "backfill" using pregnenalone. Others say that generally is ineffective. Some say most middle-aged men need some progesterone and there is now an evidence that Progesterone Can Help with Erectile Dysfunction . Still other experts say that progesterone is "estrogenic" and fights against "maleness" and should rarely if ever be given. Nevertheless, I post it here, because it is an interesting solutions.
Other significant adverse effects of testosterone supplementation include acceleration of pre-existing prostate cancer growth in individuals who have undergone androgen deprivation; increased hematocrit , which can require venipuncture in order to treat; and, exacerbation of sleep apnea .  Adverse effects may also include minor side-effects such as acne and oily skin, as well as, significant hair loss and/or thinning of the hair, which may be prevented with 5-alpha reductase inhibitors ordinarily used for the treatment of benign prostatic hyperplasia , such as finasteride .  Exogenous testosterone may also cause suppression of spermatogenesis , leading to, in some cases, infertility.  It is recommended that physicians screen for prostate cancer with a digital rectal exam and prostate-specific antigen (PSA) level before starting therapy, and monitor PSA and hematocrit levels closely during therapy.