The adrenal glands produce three types of steroid hormones: corticosteroids ("stress hormones"), androgens and mineralocorticoids. Steroid production occurs in steps; for example, progesterone can be made into the corticosteroids cortisol or corticosterone, and corticosterone can produce the mineralocorticoid aldosterone. In congenital adrenal hyperplasia (CAH), the adrenal glands do not produce the normal ratios of the different types of hormones.
Types
According to the Merck Manual, 21-hydroxylase deficiency causes 90 percent of cases of CAH. Without the enzyme 21-hydroxylase, the adrenals cannot produce the hormones cortisol or aldosterone from their precursors. In CAH, due to deficiency of 11-beta-hydroxylase, production of cortisol and corticosterone falters and their precursors build up. Some rare forms of CAH block the production of adrenal androgens, hormones needed by both sexes, but that in general produce male characteristics.
Symptoms
In total 21-hydroxylase deficiency, also called salt-wasting CAH, lack of aldosterone causes the body to lose too much salt. This can be life-threatening as levels of sodium and potassium regulate the function of the heart and maintain blood pressure. In an adrenal crisis, the patient might vomit, have diarrhea or go into shock.
Most patients with CAH do not make enough cortisol, compromising the body's ability to respond appropriately to stress, regulate blood sugar and energy levels, and maintain normal blood pressure.
Because of the excess of adrenal androgens, young girls with CAH due to total 21-hydroxylase deficiency or 11-beta-hydroxylase deficiency have abnormal looking genitals, a condition called ambiguous genitalia. The clitoris is enlarged and might look like a small penis, and the labia (vaginal lips) might be fused together. In both sexes, androgen excess from any form of CAH accelerates some pubertal changes, such as the appearance of pubic hair and acne in both sexes, and penis growth and voice changes in boys.
Cause
Congenital adrenal hyperplasia occurs when a baby inherits defective copies of a gene encoding an enzyme that produces adrenal steroids. A baby can inherit the condition from two normal healthy parents, because CAH is an autosomal recessive trait, meaning that it occurs only when there are two defective copies of the gene, one inherited from each parent.
Risk Factors
If a parent has CAH, their child has an increased risk of having CAH as well, because that parent can only contribute a defective gene. The Mayo Clinic says that Ashkenazi Jews, Hispanics, Italians, Yugoslavs and Inuits (Eskimos) have a higher prevalence of CAH.
Treatment
Daily doses of replacement hormones help patients with CAH regulate vital body processes. During stressful times, the patient will probably need higher doses to cope. Steroid drugs are powerful and can have serious side effects like suppressing body and bone growth, so the patient must be monitored closely. If androgen excess causes abnormal genitals in girls with CAH, they might require surgery to correct their function and appearance.
