Disorders of the hypothalamic-pituitary-gonadal axis

This chapter reviews the molecular basis of reproductive disorders in the human, including those that result in hypogonadism as well as eugonadism along with focus on the diagnosis and clinical features of hypothalamic-pituitary-gonadal (HPG) axis disorders. Dysfunction of the HPG axis can result in a wide range of disorders in both males and females. They are somewhat arbitrarily categorized into hypothalamic, pituitary, gonadal and outflow tract abnormalities. Patients presenting with delayed puberty, menstrual abnormalities after puberty, or suspicion for hypogonadism after puberty should have thyroid studies to exclude hypothyroidism, which is more common than hyperthyroidism. The endocrinology of eating disorders is complex, and involves the HPG axis, hypothalamic-pituitary-adrenal (HPA) axis, thyroid, growth hormone (GH), and appetite hormones. The molecular basis of uterine and vaginal development is largely unknown, as it is difficult to identify families since pregnancy and vertical transmission will not occur. For males, with outflow obstruction due to CBAVD, sperm may be retrieved from the epididymis or testis for intracytoplasmic sperm injection (ICSI) in in vitro fertilization (IVF).