title: Mechanisms of disease: late-onset hypogonadism.
abstract: Late-onset hypogonadism (formerly called the andropause) is a clinical and biochemical syndrome associated with advancing age, which is characterized by typical signs and symptoms and a deficiency in serum testosterone levels. Age-related hypoandrogenism in the male is a result of the interaction of hypothalamopituitary and testicular factors. The hypothalamic pulsatile secretion of gonadotropin-releasing hormone is blunted, due to increased hypothalamic sensitivity to inhibition by steroids, but the responsiveness of the pituitary gonadotrophs seems to be intact. In addition, testicular volume as well as Leydig cell mass and reserve function are diminished. Taken together, these mechanisms result in reduced testosterone secretion and the loss of nycthemeral variability.
authors.affiliation: Department of Medical and Urological Andrology, Ghent University Hospital, Ghent, Belgium. ahmed.mahmoud@ugent.be
authors.forename: Ahmed
authors.initials: A
authors.lastname: Mahmoud
authors.forename: Frank H
authors.initials: FH
authors.lastname: Comhaire
mesh_terms: D000367:Age Factors; D047649:Andropause / Q000187:drug effects / Q000502:physiology*; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism; D006065:Gonadotropins, Pituitary / Q000378:metabolism; D020249:Hormone Replacement Therapy; D006801:Humans; D007006:Hypogonadism / Q000188:drug therapy / Q000503:physiopathology*; D007030:Hypothalamo-Hypophyseal System / Q000503:physiopathology; D007985:Leydig Cells / Q000502:physiology; D008297:Male; D010913:Pituitary-Adrenal System / Q000503:physiopathology; D013739:Testosterone / Q000378:metabolism
chemical_list: D006065:Gonadotropins, Pituitary; D007987:Gonadotropin-Releasing Hormone; D013739:Testosterone