What Is Congenital Adrenal Hyperplasia (CAH)?

Congenital Adrenal Hyperplasia (CAH) is a defect in the adrenal gland and is most commonly caused by a deficiency in the 21-hydroxylase enzyme

There are two forms of Congenital Adrenal Hyperplasia (CAH):

  • Classical CAH
  • Non-classical CAH

Both forms of CAH are passed down in a family from the parents to the child. Parents are “carriers” – they carry the trait but have no symptoms of their own. However, they can pass on the trait to their child, and will have a 25 percent chance of having an affected child. 1 in 60 people carry an affected copy of the CAH gene.

Classical CAH

Classical CAH occurs in about one in 15,000 births and can present in newborns as either Salt-Wasting and Simple-Virilizing (not salt-wasting) types. More patients have salt-wasting CAH (~67 percent of cases) and it is more clinically severe than simple-virilizing CAH.

Children diagnosed with Classical CAH lack the adrenal gland hormone, cortisol, resulting in patients producing too much of the male hormone, testosterone. Children with salt-wasting CAH, and some with simple-virilizing, additionally lack the hormone aldosterone, which allows the kidney to maintain proper levels of salt in the body.

Symptoms of Classical CAH may include:

  • Male-looking external genitalia in newborn females.
  • Abnormal electrolytes in patients (which can lead to major clinical symptoms in both males and females).
  • Darkened appearance of skin.
  • Repetitive vomiting, abdominal pains, and diarrhea.

Children with Classical CAH can present to the doctor with signs of:

  • Low blood sugar
  • Low blood sodium
  • High blood potassium
  • Dehydration
  • Vascular collapse

Non-classical CAH

Non-classical CAH (NCAH) occurs in one in 1,000 births overall. Affected children do not typically show symptoms of CAH at birth, but may develop and show symptoms any time later in childhood and adult life. NCAH is not life-threatening.

  • Abnormalities in puberty. This can include early development of pubic hair, underarm hair, adult-type of body odor, acne; the early onset of puberty in boys (enlargement of testicles/penis) and girls (breast development)
  • Unusually fast gain in height (growth) in both girls and boys.
  • Irregular or absent menstrual periods in girls.
  • An enlarged clitoris in girls.

Symptoms of NCAH may include:

  • Excess/early pubic hair.
  • Excess facial hair.
  • Rapid height growth.
  • Enlarged penis in boys.
  • Enlarged clitoris in girls.
  • Moderate to severe acne.
  • Absence or loss of menstrual periods in young women.