The secretion of cortisol is mainly controlled by three inter-communicating regions of the body, the hypothalamus in the brain, the pituitary gland and the adrenal gland . This is called the hypothalamic–pituitary–adrenal axis. When cortisol levels in the blood are low, a group of cells in a region of the brain called the hypothalamus releases corticotrophin-releasing hormone , which causes the pituitary gland to secrete another hormone, adrenocorticotropic hormone , into the bloodstream. High levels of adrenocorticotropic hormone are detected in the adrenal glands and stimulate the secretion of cortisol, causing blood levels of cortisol to rise. As the cortisol levels rise, they start to block the release of corticotrophin-releasing hormone from the hypothalamus and adrenocorticotropic hormone from the pituitary. As a result the adrenocorticotropic hormone levels start to drop, which then leads to a drop in cortisol levels. This is called a negative feedback loop.
Sometimes, when there is a known family history of CAH, a fetus is diagnosed before birth. Prenatal treatment of CAH is experimental. There is no cure for CAH, and giving steroids to the pregnant mother is merely an attempt to reduce fetal production of male sex hormones and thereby prevent the atypical genital appearance in affected baby girls with severe forms of CAH. Many experts are concerned about the potential for as yet unknown long-term side effects of using dexamethasone, a very strong steroid, during pregnancy—even if it is for a short time.
Patients with congenital adrenal hyperplasia usually have to take lifelong steroid medication. Current treatments try to mimic normal biology as much as possible, but are not perfect. The evidence suggests that if well treated during childhood, most patients with congenital adrenal hyperplasia will reach a normal adult height but probably be a little shorter than would have been predicted if they did not have the disorder. Fertility is reduced in some patients but there are an increasing number of options for helping patients achieve fertility. Reconstruction genital surgery might be required in older girls with ambiguous genitalia. Maintaining the right balance of steroids is important during adult life to avoid the complications of osteoporosis , obesity and hypertension.