Androgen deficiency in the aging male: when to evaluate and when to treat.

Aging can be associated with an abnormal decline in testosterone production, mainly due to pituitary failure, and is reflected by low serum testosterone concentrations. Manifestations of testosterone deficiency can be subtle, can be misinterpreted as consequences of normal aging, and include lack of libido and energy, mood changes, impaired strength, and development of osteoporosis. The most important factor in the evaluation and treatment of this age-related, usually unrecognized abnormality is the public awareness of its frequent occurrence that will stimulate the use of appropriate screening tests, beginning with a morning testosterone level. Replacement therapy by parenteral or transdermal testosterone administration can be highly beneficial in alleviating the manifestations of hypogonadism and improving quality of life. Careful screening and meticulous follow-up are mandatory. The long-term effects of testosterone replacement on the cardiovascular system, the prostate, and on longevity are unknown.