Introduction to Endocrine Disorders in Men

Abstract

Male hypogonadism is a condition in which testosterone production or action is impaired, or insufficient numbers of sperm are produced, or both. Hypogonadism in the male fetus disrupts the process of sexual differentiation. If the condition begins in childhood, puberty is incomplete or delayed or does not occur, while adult men with hypogonadism may present with poor libido, a regression of secondary sexual characteristics, or infertility. Each of these conditions is often evaluated by endocrinologists. Males will be hypogonadal if there is a disorder of the testis (primary testicular failure) or of the hypothalamic-pituitary unit (hypogonadotropic hypogonadism). Many clinical conditions affect both compartments, however. Adult onset hypogonadism (AOH) is a syndrome of middle-aged to older men who have symptoms consistent with testosterone deficiency and borderline-low total testosterone levels. There is primary testicular dysfunction, especially as men grow older, subtle changes in GnRH-LH secretion and a decrease in testosterone levels because the transport protein, SHBG, is suppressed with insulin resistance. The diagnosis and treatment of AOH remain controversial. Three illustrative cases are presented and discussed.