Hypogonadism in untreated male normoprolactinaemic acromegalics

Hypogonadism is a distinct feature of acromegaly, even in the absence of hyperprolactinaemia. In 10 untreated male acromegalics, aged 24 to 46 yr, without evidence of any other disturbance of anterior pituitary function, low testosterone values were found in the presence of a normal reaction of pituitary gonadotrophins following GnRH administration. In three patients, one injection of 5000 IU hCG resulted in a sharp rise in testosterone. Although we were unable to elicit a similar reaction pattern of the GnRH-gonadotrophins-testosterone axis following administration of biosynthetic methionyl-hGH, it is suggested that suppression of testicular function in untreated acromegaly without other endocrine disturbances may be partly caused by increased somatostatin production.