Congenital Adrenal Hyperplasia (CAH) – an Overview | Endocrinology

Congenital Adrenal Hyperplasia (CAH)

What is congenital adrenal hyperplasia?

Congenital adrenal hyperplasia (CAH) refers to a group of genetic defects that affect the adrenal glands of walnut-sized organs above the kidneys. The adrenal glands produce important hormones, including:

  • Cortisol, which regulates the body’s response to illness or stress.
  • Mineral corticosteroids such as aldosterone that regulate sodium and potassium levels
  • Androgens like testosterone are male sex hormones
  • In people with CAH, a genetic problem causes a lack of one of the enzymes needed to make these hormones.
  • Even without treatment, with proper treatment, most people with congenital adrenal hyperplasia can lead normal lives.

There are two main types of congenital adrenal hyperplasia:

  • Classic CAH: This form is very rare and is usually found in childhood. Two-thirds of people with classic CAH call it the salt-losing form, while one-third call it the normal virilizing form.
  • Non-classical CAH: This form is mild and common, and may not be apparent until childhood or adolescence.

Types of congenital adrenal hyperplasia

Classic CAH

According to the National Adrenal Disease Foundation, classic CAH accounts for 95 per cent of all CAH cases. It occurs mainly in babies and young children. The adrenal glands produce cortisol and aldosterone with the help of an enzyme commonly known as 21-hydroxylase. Classic CAH does not have this enzyme, which means that your adrenal glands cannot make these hormones.

Also, your body begins to produce more male sex hormone called testosterone. It can appear in girls with masculine features and develop early in boys. These characteristics are:

  • Be tall for your age
  • Have a deep tone
  • Early growth of pubic or armpit hair
  • CAH in childhood can make you taller than other children, and as an adult, you may be slightly shorter than average.

Nonclassic or late-onset CAH

Nonclassic or late-onset CAH is a mild type that occurs in older children and adolescents. This type is caused by a partial enzyme deficiency rather than a complete absence of the enzyme. If you have this type of CAH, your adrenal glands can make aldosterone, but not enough cortisol. Testosterone levels are also lower in late-onset CAH.

Rare forms

There are other types of CAH, but they are very rare. These include deficiencies of 11-beta-hydroxylase, 17-alpha-hydroxylase, and 3-beta-hydroxysteroid dehydrogenase

Symptoms of congenital adrenal hyperplasia

The signs and symptoms of CAH vary depending on the defective gene and the level of the enzyme defect.

Classic CAH

Girls with classic CAH may have a condition called dark genitalia, in which the vagina expands or the genitals look like boys. Male babies with classic CAH have normal genitalia. Male and female babies are severely affected by a lack of cortisol, aldosterone, or both. This is called an adrenal crisis and it can be fatal.

The salt-wasting form and classic form of virilization of classic CAH cause children’s bodies to produce enough cortisol. These children have trouble maintaining normal blood pressure, blood sugar, and energy levels and are more prone to stress. Excess male sex hormones lead to shorter stature and early puberty in both boys and girls.

Signs and symptoms of classic CAH in children and adults:

  • The appearance of pubic hair at a very young age.
  • Rapid growth in childhood, but lower than average final height

Non-classical CAH

Non-classical CAH symptoms often do not appear when the baby is born. This condition is not detected in a regular infant blood test and is usually evident in late childhood or early adulthood. Cortisol may be the only hormone deficient.

Adolescent and adult women with nonclassic CAH may have normal genitalia at birth, but later in life, they may experience:

  • Irregular or absent period
  • Male traits such as facial hair, tall body hair, and deep voice
  • Sharp pimples

In both men and women, there may be signs of non-classical CAH:

  • The early appearance of pubic hair
  • Predicts rapid growth in childhood, developed bone age, and short final stature

Congenital adrenal hyperplasia causes

The most common cause of CAH is the lack of an enzyme called 21-hydroxylase. CAH is sometimes called a 21-hydroxylase deficiency. Other very rare enzyme deficiencies cause CAH.

Children with this condition have two parents, who either have CAH or are carriers of the genetic mutation that causes this condition. This is called an autosomal recessive inheritance pattern.

Congenital adrenal hyperplasia risk factors

Factors that increase the risk of CAH:

  • Both parents have CAH or both are carriers of the genetic defect of the disorder.
  • Ashkenazi has some ethnic heritage, such as Jewish, but Hispanic, Italian, Yugoslav, and Yupik Inuit

How is congenital adrenal hyperplasia diagnosed?

A prenatal ultrasound can detect CAH before a baby is born. But it is generally congenital or based on symptoms (such as abnormally visible genitalia) or US Newborn screening performed on all newborns is suspected based on the results of blood tests.

A pediatric endocrinologist will usually check that the baby does not have adrenal enzymes and prescribe treatment.

Tests to help diagnose CAH or guide treatment may include:

  • Blood tests to check adrenal hormone levels.
  • Blood Chemistry to Check for High Sodium and Potassium Levels in Children with CAH Salt Loss
  • Karyotype to determine chromosomal sex
  • Imaging tests (such as an ultrasound study) to learn more about genital anatomy
  • X-rays to see how fast the bones are maturing

In infancy or later diagnosis may include:

  • History and physical exam
  • Blood test
  • Genetic testing

Sometimes when a family history of CAH is known, the fetus is diagnosed before birth. The experimental prenatal treatment of CAH is a controversial experiment and experts recommend that it be done only in the context of an approved clinical trial.

Treatment of congenital adrenal hyperplasia

Your doctor will refer your child to a doctor who specializes in pediatric hormonal problems (pediatric endocrinologist) for the treatment of CAH. The healthcare team may also include other professionals such as urologists, psychologists, and geneticists. 


The goal of treating congenital adrenal hyperplasia with medication is to reduce the production of excess androgens and replace the defective hormones. People with the classic form of CAH can successfully manage the condition through hormone replacement therapy for the rest of their lives. People with nonclassical CAH may not need treatment or only need a small dose of corticosteroids.

Medications for congenital adrenal hyperplasia are taken daily. During periods of significant stress, such as illness or surgery, additional medications or higher doses may be needed.

Medications can include:

  • Corticosteroids instead of cortisol
  • Mineral corticosteroids replace aldosterone to retain salt and remove excess potassium
  • Medicines with salt to retain salt.

Monitoring of the effects of Action is regularly scheduled:

  • Physical exams: The doctor will monitor your child’s growth and development, including monitoring changes in height, weight, blood pressure, and bone growth.
  • Side effect monitoring: The doctor will monitor your child for side effects such as bone loss and growth retardation, especially if the dose of the steroid-type replacement medication is high and if it is used chronically.
  • Blood tests to check hormone levels: Regular blood tests are essential to ensure hormone levels are in balance. Boys who have not yet reached puberty need enough cortisone to suppress androgens so that they can reach normal heights. For women with congenital adrenal hyperplasia, it is important to suppress androgens to reduce unwanted male symptoms. On the other hand, too much cortisone can cause Cushing’s syndrome.

Reconstructive surgery

  • For some girls who have very blurry genitalia as a result of classic CAH, doctors may recommend reconstructive surgery to improve genital function and make them look more feminine.
  • Surgery may include reducing the size of the clitoris and rebuilding the vaginal opening. Surgery is usually done at 2 and 6 months of age. Women who have had reconstructive genital surgery may need more cosmetic surgery in the future.
  • Genital surgery is easier to do when the child is very young. However, some parents choose to wait for surgery until their child is old enough to understand the risks and choose their gender.
  • Before making decisions about the best treatment for your child, talk to your doctor about these issues. Working together, you and your doctor can select the information that will help your child’s development.
  • Psychological support is important for the mental health and social adjustment of girls with genital disabilities.

Prenatal treatment

Synthetic corticosteroids that cross the placenta are controversial and considered experimental. More research is needed to determine the safety and long-term effect of this treatment on fetal brain development.

Complications of congenital adrenal hyperplasia

People with classic CAH are at risk for an adrenal crisis because they have very low levels of cortisol in their blood. It can cause diarrhea, vomiting, dehydration, high blood sugar, and shock. Adrenal crisis is a life-threatening medical emergency that requires immediate treatment. Aldosterone can also below, leading to dehydration and low sodium and high potassium levels. The nonclassic form of congenital adrenal hyperplasia does not cause the adrenal crisis.

Men and women with classic or non-classic CAH also experience fertility problems.


There is no known way to prevent congenital adrenal hyperplasia. If you are thinking about starting a family and are at risk of having children with congenital adrenal hyperplasia, your doctor may recommend that you see a genetic counsellor.

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