PHYSICAL EXAMINATION

LABORATORY STUDIES

DIAGNOSIS

Secondary hypogonadotropic hypogonadism

PATHOPHYSIOLOGY OF KEY SYMPTOMS

Gonadotropin-releasing hormone (GnRH) is produced and secreted by neurons in the hypothalamus and travels through the hypothalamohypophyseal portal system to the anterior pituitary to stimulate the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) (Fig. 85-1). The reproductive cells and glands are the targets for FSH and LH. For females, FSH stimulates ovarian follicles to mature and to release estrogen. For males, FSH stimulates testicular Sertoli cells to produce paracrine molecules necessary for the mitosis of spermatogonia into mature sperm. For females, LH stimulates the corpus luteum to secrete progesterone. For males, LH stimulates testicular Leydig cells to secrete testosterone.

FIGURE 85–1 Feedback regulation of the hypothalamic-pituitary-testicular axis in males. Stimulatory effects are shown by and negative feedback inhibitory effects are shown by . GnRH, Gonadotropin-releasing hormone; LH, luteinizing hormone; FSH, follicle-stimulating hormone.