An area of the brain called the hypothalamus secretes gonadotropin-releasing hormone (GnRH), which stimulate the pituitary gland. In response to this hormone, the pituitary gland (located near the hypothalamus) secretes other hormones (FSH and LH). These hormones, in turn, stimulate the ovaries (female) and testes (male) to secrete hormones that are responsible for normal sexual development in puberty. Any disruption in this chain reaction causes a deficiency of the sex hormones and halts normal sexual maturation. Failure of the hypothalamus is most commonly a result of Kallmann syndrome. Kallmann syndrome is an inherited disorder that usually includes a disorder of the sense of smell. Failure of the pituitary may result from empty sella syndrome, pituitary tumors (craniopharyngioma), head injuries, or other causes.
| 
