Hypogonadotropic hypogonadism is absent or decreased function of the male
Gonadotropin deficiency; Secondary hypogonadism; Kallmann syndrome
Causes, incidence, and risk factors
Hypogonadotropic hypogonadism is caused by a lack of the gonadal stimulating pituitary hormones: follicle stimulating hormone (FSH) and luteinizing hormone (LH).
Normally, the hypothalamus in the brain releases gonadotropin-releasing hormone (GnRH), which stimulates the pituitary gland to release other hormones, including FSH and LH. These hormones tell the female ovaries and male testes to secrete hormones that are responsible for normal sexual development in puberty. A disruption in this chain of events causes a deficiency of the sex hormones and prevents normal sexual maturity.
Failure of the hypothalamus is most commonly a result of Kallmann syndrome. Kallmann syndrome is an inherited form of hypogonadotropic hypogonadism that can be associated with a loss of smell.