Ontogeny of Gonadotropin Secretion in Congenital Anorchism: Sexual Dimorphism Versus Syndrome of Gonadal Dysgenesis and Diagnostic Considerations

The hormonal characteristics of anorchism are elevated basal levels of gonadotropins, especially follicle-stimulating hormone and a low concentration of plasma testosterone that fails to increase after the administration of human chorionic gonadotropin. However, little is known about the dynamics of plasma gonadotropin secretion in infants and children with anorchism. We analyzed plasma gonadotropin concentrations and their responses to luteinizing hormone releasing factor, along with plasma testosterone responses to human chorionic gonadotropin, in 9 children with surgically proved bilateral anorchism. Basal concentrations of gonadotropins, especially plasma follicle-stimulating hormone, are elevated above normal during the first 3 to 4 years of life, decrease gradually to normal prepubertal levels and then increase again after age 9 years. This age-dependent diphasic pattern of gonadotropin secretion is comparable to that described previously in patients with the syndrome of gonadal dysgenesis and it is consistent with steroid-independent central nervous system inhibition of pulsatile luteinizing hormone releasing factor secretion during mid childhood. Moreover, a sex difference in follicle-stimulating hormone and luteinizing hormone values was observed; the mean follicle-stimulating hormone and luteinizing hormone concentrations in anorchid boys less than 3 years old were lower than in patients with Turner’s syndrome. We suggest that this sex dichotomy is a consequence, at least in part, of the actions of testosterone derived from the fetal testis on the fetal hypothalamus.