Hypogonadotropic hypogonadism

Hypogonadotropic hypogonadism (HH), also known as secondary or central hypogonadism, as well as gonadotropin-releasing hormone deficiency or gonadotropin deficiency (GD), is a condition which is characterized by hypogonadism due to an impaired secretion of gonadotropins, including follicle-stimulating hormone (FSH) and luteinizing hormone (LH), by the pituitary gland in the brain, and in turn decreased gonadotropin levels and a resultant lack of sex steroid production.

The type of HH, based on its cause, may be classified as either primary or secondary. Primary HH, also called isolated HH, is responsible for only a small subset of cases of HH, and is characterized by an otherwise normal function and anatomy of the hypothalamus and anterior pituitary. It is caused by congenital syndromes such as Kallmann syndrome, CHARGE syndrome, and gonadotropin-releasing hormone (GnRH) insensitivity. Secondary HH, also known as acquired or syndromic HH, is far more common than primary HH, and is responsible for most cases of the condition. It has a multitude of different causes, including brain or pituitary tumors, pituitary apoplexy, head trauma, ingestion of certain drugs, and certain systemic diseases and syndromes.

...
Wikipedia