AHN - What is CAH
What is Congenital Adrenal Hyperplasia?
The adrenal gland sits above each kidney ? one on each side of the body. It is made up of a medulla (middle) which makes adrenaline ? this part works perfectly normally in CAH. The outer part of the adrenal gland is the adrenal cortex which makes three main hormones called steroids. These steroids are secreted into the blood stream and are necessary for normal health. It is the adrenal cortex and its hormones which are involved in CAH.
The 3 main steroids involved in CAH are:
There are five main enzymes in the adrenal gland which convert cholesterol into the important steroid cortisol. If any of these enzymes are missing or defective then not enough cortisol is made for the needs of the body. The body, recognising the low levels of cortisol, will try to stimulate the adrenal cortex to make more by ?pushing? the gland harder by a stimulating
hormone called ACTH made in the pituitary gland. The constant unsuccessful stimulation causes the cortex to increase in thickness and become ?hyperplastic?.
In the most common form of CAH there is a deficiency of an enzyme called 21 hydroxylase. In this form of CAH the production of cortisol and aldosterone is low while testosterone, the male hormone, is produced normally. As the body pushes the adrenal gland harder trying to correct the low cortisol level more and more testosterone is made. In boys, this excess of testosterone causes early sexual development. In females, the excess in testosterone can cause abnormal genital development before birth while in adults it causes irregular periods, unwanted hair growth and acne. Only by correcting the levels of cortisol with substitute therapy does the body recognise normal levels and stop producing excessive amounts of testosterone and the circulating levels become normal.
The hormone disturbances caused by CAH:
? Dr G. S. Conway 1999
This Page was updated 21 May 2018
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