ADULT-ONSET IDIOPATHIC HYPOGONADOTROPIC HYPOGONADISM - A TREATABLE FORM OF MALE-INFERTILITY

Background Men with isolated gonadotropin-releasing hormone (GnRH) def iciency typically present with an absence of pubertal development. We describe an adult-onset form of idiopathic hypogonadotropic hypogonadi sm that develops after puberty. Methods We studied 10 men (age, 27 to 57 years) with normal sexual maturation, idiopathic infertility, sexua l dysfunction, low serum testosterone concentrations, and apulsatile s ecretion of luteinizing hormone on frequent blood sampling. All the me n had otherwise normal anterior pituitary hormone secretion and sellar anatomy. We compared the results of semen analyses and measurements o f testicular volume, serum testosterone, inhibin B, and gonadotropins in these men with the results in 24 men with classic GnRH deficiency b efore and during GnRH-replacement therapy and in 29 normal men of simi lar age. Results Serum gonadotropin concentrations in the men with adu lt-onset GnRH deficiency were similar before and during pulsatile GnRH administration to those in the men with classic GnRH deficiency. Howe ver, as compared with men with classic GnRH deficiency, men with adult -onset hypogonadotropic hypogonadism had larger mean (+/-SD) testicula r volumes (18+/-5 vs. 3+/-2 ml, P<0.001), serum testosterone concentra tions (78+/-34 vs. 49+/-20 ng per deciliter [2.7+/-1.2 vs. 1.7+/-0.7 n mol per liter], P=0.004), and serum inhibin B concentrations (119+/-52 vs. 60+/-21 pg per milliliter, P<0.001). Treatment with GnRH reversed the hypogonadism and restored fertility in each of the five men who r eceived long-term therapy. Conclusions The recognition of adult-onset hypogonadotropic hypogonadism in men as a distinct disorder expands th e spectrum of GnRH deficiency and identifies a treatable form of male infertility. (C) 1997, Massachusetts Medical Society.