Androgen Deficiency in Men

Testosterone levels fall as men age, and testosterone deficiency in men is being recognized with increased frequency. Many of the symptoms and signs of testosterone deficiency can be observed with other conditions. The majority of men with low testosterone levels are 65 years of age and older, and most have low or inappropriately normal serum luteinizing hormone levels. However, few have detectable anatomic brain abnormalities on magnetic resonance imaging, so the etiology usually is unknown. The laboratory diagnosis of testosterone deficiency often is complicated by changes in sex-hormone binding globulin (SHBG) levels that accompany aging (increase in SHBG) and obesity (decrease in SHBG), so accurate measurements of free or bioavailable testosterone are required. In addition to diseases of the hypothalamus, pituitary, and testes, the prevalence of testosterone deficiency is also increased in many chronic medical conditions, such as obesity, type 2 diabetes mellitus, chronic liver and renal disease, and various inflammatory diseases. Testosterone replacement may improve the quality of life, but the benefits and risks of treatment have not been evaluated in large clinical trials. This is especially important in older men, where the risks of treatment are greater. This review addresses these issues, as well as advantages and disadvantages of available testosterone delivery systems. Careful and regular monitoring is essential to ensure adequacy of treatment and to minimize the risks of treatment.