Disturbances of the hypothalamic—pituitary—gonadal axis are reviewed in patients with Prader—Willi syndrome, and a brief account is given of thyroid function, adrenal function and glucose metabolism in such patients. Cryptorchidism, hypoplastic external genitalia and
delayed or incomplete pubertal development in most patients with Prader—Willi syndrome suggest dysfunction of the hypothalamic—pituitary—gonadal axis. Decreased levels of gonadotrophins, consistent with hypogonadotrophic hypogonadism, have been found in some patients, whereas
others appear to have hypergonadotrophic hypogonadism secondary to cryptorchidism and its treatment. Gonadal function is normal in a small number of patients with the syndrome. Although most clinicians agree that cryptorchidism should be corrected in early childhood, in practice the surgery
is often not performed. In addition, most patients do not receive sex hormone replacement therapy. It is therefore suggested that more aggressive endocrine treatment strategies for hypogonadism are warranted in both children and adults with Prader—Willi syndrome. Both thyroid function
and adrenal function appear to be normal in most patients, and glucose metabolism is similar to that in normal obese individuals.