In either sex, abnormally high production of male sex hormones by the adrenal glands
- Present from birth
- Due to an abnormal gene inherited from both parents
- Gender and lifestyle are not significant factors
Congenital adrenal hyperplasia is a rare inherited condition that affects around 1 in 5,000 babies in the UK. In congenital adrenal hyperplasia, the production of one or more hormones in the adrenal glands is abnormal.
In the most common form of congenital adrenal hyperplasia, there is a deficiency of an enzyme that is essential for the production of the adrenal hormones aldosterone, which maintains the salt and water balance in the body, and cortisol, which maintains glucose levels in the blood. As a result, these hormones may be absent or deficient. The condition also leads to excessive production of male sex hormones (androgens).
Congenital adrenal hyperplasia is caused by an abnormal gene that is inherited in an autosomal recessive manner (see Gene disorders).
What are the symptoms?
The symptoms of congenital adrenal hyperplasia may be present at birth or may develop later in childhood or adolescence. Raised levels of androgens may lead to the following symptoms:
In girls, an enlarged clitoris and external genitals that are fused, giving a masculinized appearance.
In boys, a slight increase in pigmentation of the scrotum, which often goes unnoticed.
Early puberty in boys.
Lack of aldosterone may cause a “salt-losing crisis” in which there is a sudden loss of salt and fluid. The symptoms of such a crisis may include:
Loss of weight.
What might be done?
Congenital adrenal hyperplasia is usually diagnosed in girls at birth from the appearance of the genitals. The disorder may become apparent in boys due to a salt-losing crisis developing 1–3 weeks after birth.
An affected child will have blood tests to measure the levels of hormones, salt, and glucose. If a baby has a salt-losing crisis, he or she will require emergency treatment in hospital with intravenous salt and glucose solutions. Cortisol and a drug that mimics the actions of aldosterone will also be given. A child who has congenital adrenal hyperplasia will require lifelong treatment to replace the deficient hormones and to normalize the production of androgens. Affected girls may need to have surgery to correct genital abnormalities.
With treatment, most children with congenital adrenal hyperplasia can lead normal lives. A pregnant woman who has already given birth to a child with the disorder may be offered screening tests, and, if necessary, drug treatment may be prescribed to minimize the effects of the condition on a female fetus.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.
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