Hypogonadotropic hypogonadism in idiopathic hemochromatosis: evidence for combined hypothalamic and pituitary involvement.

Hypogonadism is a common finding in idiopathic hemochromatosis. Most studies have localized the defect to either the pituitary gland or the testes. We describe a case with evidence that favors the likely concomitant involvement of the hypothalamus as a factor in the observed hypogonadism. A clinically hypogonadal male with hemochromatosis had a low testosterone concentration with inappropriately normal serum LH levels. Leydig cell function was intact, as demonstrated by a normal increase in serum testosterone following HCG administration. However, although the pituitary secretion of LH was normal in response to GnRH stimulation, clomiphene administration did not produce an increase in LH and FSH, suggesting that there was a defect in the hypothalamic GnRH response. Since the FSH and prolactin responses to stimulatory testing were inadequate, coexisting pituitary dysfunction was likely also present. We conclude that this man had hypogonadism with laboratory evidence for a combined defect in hypothalamic and pituitary function.