Male hypogonadism due to disorders of the pituitary and suprasellar region

Abstract

Male hypogonadism is a clinical condition in which there is insufficient testosterone production, and/or hypospermatogenesis. Testicular testosterone production is regulated by hypothalamic–pituitary–gonadal axis in which GnRH stimulates gonadotrophs of the anterior pituitary to produce and secrete the gonadotropins FSH and LH. LH stimulates Leydig cells to produce testosterone, and FSH stimulates receptors on Sertoli cells. Pathological conditions affecting the pituitary or suprasellar region can cause hypogonadism characterized by low testosterone and low/low-normal LH levels as well as deficiency of other pituitary hormones. A thorough pituitary evaluation (hormonal investigation and MR/TC) is therefore mandatory when there is evidence for central hypogonadism. This chapter describes the disorders of the pituitary and suprasellar region that produce male hypogonadism, including functional and non-functional pituitary adenomas, non-pituitary and parasellar tumors, and non-neoplastic causes of hypogonadotropic hypogonadism, with respect to prevalence, diagnosis, clinical presentation and therapy.