What is Congenital Adrenal Hyperplasia?
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.
3 main steroids involved in CAH are:
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
called ACTH made in the pituitary gland. The
constant unsuccessful stimulation causes the cortex to increase in thickness and
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.
hormone disturbances caused by CAH:
© Dr G. S. Conway 1999
This Page was updated 16-Jul-2004
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