What is congenital adrenal hyperplasia (CAH)?

Congenital adrenal hyperplasia (CAH) describes a group of genetic disorders affecting your adrenal glands. You have one adrenal gland on top of each kidney. The adrenal glands produce several important hormones your body needs.

In CAH, genetic mutations (changes) cause shortages of certain enzymes, such as 21-hydroxylase, that help your body produce needed hormones. For many people with CAH, the enzyme shortage causes the adrenal glands to overproduce other hormones, like testosterone.

There are two main types of CAH: classic CAH and nonclassic CAH. The symptoms depend on the type of CAH you have. There are much more rare forms of CAH with different symptoms.

Who is most at risk for getting congenital adrenal hyperplasia (CAH)?

Congenital means a condition you are born with. All forms of CAH are genetic, or inherited. To develop CAH, you must inherit certain genetic mutations from each of your parents.

How common is congenital adrenal hyperplasia (CAH)?

Classic CAH, the most common form of the disease, affects as many as 1 in every 10,000 to 15,000 people living in the U.S. and Europe. Both classic and nonclassic CAH affect people worldwide.

What causes congenital adrenal hyperplasia (CAH)?

Specific genetic mutations cause CAH. These genetic changes happen during a baby’s development in the womb. People living with CAH have all inherited mutated genes from their parents.

What are the symptoms of congenital adrenal hyperplasia (CAH)?

The symptoms of CAH may appear differently depending on factors including your age at diagnosis, and whether you are male or female. Each type of CAH has different symptoms.

Classic CAH

For people living with classic CAH, symptoms occur due to a lack of the enzyme 21-hydroxylase. Doctors group classic CAH into 2 subcategories: salt-wasting CAH and simple virilizing (non-salt-wasting) CAH.

Salt-wasting CAH is the most severe form of this disease. People living with salt-wasting CAH have adrenal glands that don’t produce enough aldosterone, a hormone that helps regulate sodium (salt) levels in the body. Low levels of aldosterone result in too much sodium being lost from the body in urine.

The hormonal imbalances caused by salt-wasting CAH result in severe symptoms, including:

  • Dehydration
  • Hyponatremia (low blood sodium levels)
  • Cardiovascular problems, including low blood pressure and arrhythmias (heart rhythm problems)
  • Vomiting
  • Low blood glucose (blood sugar)
  • Metabolic acidosis (too much acid content in the blood)
  • Shock

Additionally, people living with salt-wasting CAH have high levels of androgens, or male sex hormones, in their bodies. Elevated androgen levels cause other symptoms, including:

  • Enlarged or ambiguous (abnormal) external genitalia—for example, clitoris enlargement in a female infant
  • Rapid growth
  • Premature signs of puberty, including voice changes, early pubic, armpit, and facial hair, and severe acne
  • Abnormal menstrual periods
  • Noncancerous testicular tumors
  • Infertility

Simple virilizing (non-salt-wasting) CAH causes a less-severe aldosterone deficiency. Androgen levels are also elevated in this type of CAH. Symptoms of simple virilizing CAH may include:

  • Ambiguous (unusual) external genitalia, particularly in females
  • Development of male characteristics, such as bulky muscles and a deep voice, in females or prematurely in boys

Nonclassic CAH

People with nonclassic CAH also have too little 21-hydroxylase enzyme activity, but this deficiency isn’t as severe as in other forms of the disease. You may be unaware you have this form of CAH because your symptoms are more mild. Children, teenagers and adults are all diagnosed with nonclassic CAH.

The symptoms of nonclassic CAH include:

  • Early signs of puberty, including acne and excess facial or body hair in females
  • Rapid growth in childhood and as a teenager
  • Irregular menstrual periods
  • Male-pattern baldness
  • Early puberty changes in a boy, for example early pubic hair and an enlarged penis but with small testicles
  • Infertility

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