Fertile eunuch syndrome versus classic hypogonadotrophic hypogonadism.

The functioning of the hypothalamo-pituitary-target organs axis was assessed in 3 patients with 'fertile eunuch' syndrome (FE) and 6 patients with 'classic' hypogonadotrophic hypogonadism (HH) with or without hyposmia. Both groups of patients did not differ from each other with regard to basal serum prolactin levels, pituitary growth hormone and thyrotrophin reserve and the thyroid or adrenal gland function. Both groups differed, however, with respect to the hypothalamo-pituitary-gonadal function: 1. the pituitary LH response to exogenous LH-RH was (low)-normal in FE and blunted in HH; 2. the basal FSH levels were normal in FE and undetectable in HH; 3. the basal LH levels were normal in FE and 3/6 patients with HH and low in the remaining three; 4. the basal and HCG stimulated plasma testosterone concentrations were significantly higher in FE than HH. The data suggest that FE represents a less severe form of LH-RH deficiency, rather than a distinct disorder.