Imagine your body’s adrenal glands as tiny factories that produce essential hormones, like cortisol and aldosterone, which help manage stress, regulate metabolism, and maintain salt balance. In congenital adrenal hyperplasia (CAH), these factories aren’t working quite right, leading to an imbalance in hormone production.

The two main types of CAH are classic and nonclassic. More than 95 percent of people with CAH have one of these two types. However, there are also several less common types of CAH.

People with CAH have a shortage or lack of a specific enzyme, a protein that the adrenal glands need to make one or more important hormones. These hormones may include cortisol, aldosterone, and androgens such as testosterone. Without proper levels of one or more of these hormones, the body can’t develop or function properly.

There are several different genetic mutations (changes, or variants) that can lead to defective enzymes seen in types of CAH. Different variants affect different enzymes and can cause different symptoms.

Continue reading to learn more about classic, nonclassic, and uncommon types of CAH.

1. Classic CAH

Classic CAH is the most severe form of CAH. In the United States, all newborns are given genetic testing for classic CAH during a newborn screening test and are usually diagnosed right after birth.

Cause of Classic CAH

Classic CAH is also called 21-hydroxylase deficiency. This is because classic CAH is caused by a shortage or lack of the enzyme 21-hydroxylase. This enzyme helps your adrenal glands make the hormone cortisol.

About 75 percent of people with classic CAH have an inactive form of the 21-hydroxylase enzyme. Without any enzyme activity, the adrenal glands also don’t make enough of the hormone aldosterone. Aldosterone regulates salt and water levels in your body. Without enough aldosterone, your body can get rid of too much salt through your urine. That’s why this form of classic CAH is sometimes referred to as “salt-wasting CAH.”

About 25 percent of people with classic CAH have some enzyme activity, even at very low levels. With some 21-hydroxylase enzyme activity, the adrenal glands can make some aldosterone, allowing for the regulation of salt and water levels. This form of classic CAH is sometimes referred to as “non-salt-wasting CAH” or “simple virilizing CAH.”

In addition to changes in aldosterone levels, people with classic CAH can also have higher-than-normal levels of androgen — a hormone that regulates sexual development.

Symptoms of Classic CAH

The symptoms of classic CAH are related to changes in hormone levels.

If you can’t make enough cortisol, it’s difficult to maintain healthy blood pressure, blood sugar, and energy levels. Without treatment, people with classic CAH are at risk for a life-threatening condition called an adrenal crisis.

Low levels of aldosterone can cause:

• Dehydration
• Low blood volume
• Low blood pressure

According to Cleveland Clinic, too much androgen can cause problems with how children grow and develop, including:

• Early puberty
• Rapid growth initially but shorter-than-expected adult height
• Ambiguous genitalia in infants assigned female at birth
• Enlarged penis in infants assigned male at birth
• Severe acne

According to Mayo Clinic, too much androgen can also result in infertility — making it harder for women to get pregnant, and men may also have fertility issues.

2. Nonclassic CAH

Nonclassic CAH is the most common form of CAH. This type of CAH is usually milder than classic CAH.

Nonclassic CAH may not be diagnosed until childhood or early adulthood when symptoms start because it isn’t always found in newborn tests.

Cause of Nonclassic CAH

Nonclassic CAH is also caused by a 21-hydroxylase deficiency. However, the 21-hydroxylase enzyme is still able to help make some cortisol in people with nonclassic CAH.

People with the nonclassic form of CAH may have higher-than-normal androgen levels.

Symptoms of Nonclassic CAH

Some people with nonclassic CAH may not have any symptoms if they’re still about to make some cortisol. When symptoms do occur, they usually appear in late childhood or early adulthood.

The symptoms of nonclassic CAH are related to an overproduction of the hormone androgen and may include:

• Early puberty
• Severe acne
• Rapid growth in childhood
• Shorter-than-expected adult height
• Excess facial or body hair
• Irregular menstrual periods
• Difficulty getting pregnant
• Male-pattern baldness
• Enlarged penis with small testicles

3. 11-Beta-Hydroxylase Deficiency

11-beta-hydroxylase deficiency causes about 5 percent of CAH. This form of CAH is more common in Jews with Moroccan ancestry compared to the general population.

11-beta-hydroxylase deficiency can also be divided into subtypes of classic and nonclassic forms. The classic form of 11-beta-hydroxylase deficiency is usually more severe than the non-classic form. The classic form is also more common than the nonclassic form.

Cause of 11-Beta-Hydroxylase Deficiency

This form of CAH is caused by a shortage of the enzyme 11-beta-hydroxylase, which helps make cortisol and corticosteroids. Low levels of 11-beta-hydroxylase cause the body to have trouble finishing the production of cortisol and corticosteroids. Instead, the building blocks or ingredients meant for these hormones accumulate and are changed into androgen hormones. This process results in low levels of cortisol and corticosteroids and high levels of androgen hormones.

Symptoms of 11-Beta-Hydroxylase Deficiency

Many of the symptoms of 11-beta-hydroxylase deficiency are similar to 21-hydroxylase deficiency, such as ambiguous female genitalia, rapid growth, and early puberty.

In addition to symptoms related to increased androgens, 11-beta-hydroxylase deficiency can cause hypertension (high blood pressure) and low levels of potassium in the blood.

4. 17a-Hydroxylase Deficiency

17a-hydroxylase deficiency is a condition that causes CAH and also affects the development of the testicles and ovaries.

17a-hydroxylase deficiency accounts for about 1 percent of all cases of CAH.

Cause of 17a-Hydroxylase Deficiency

This form of CAH is caused by a complete or partial loss of activity from the enzyme 17a-hydroxylase, or 17-OHP. This enzyme helps to make:

• Mineralocorticoids such as aldosterone
• Cortisol
• Testosterone and estrogen

A 17a-hydroxylase deficiency affects both the adrenal glands and gonads because this enzyme is found in both types of glands.

Symptoms of 17a-Hydroxylase Deficiency

Per MedlinePlus, a website that provides health information, hormone imbalance caused by 17a-hydroxylase enzyme deficiency can cause symptoms, including:

• High blood pressure
• Low potassium levels
• Underdeveloped uterus and ovaries in females
• Lack of breasts, pubic hair, and menstruation in females
• Males with external genitalia that appear female
• Testicles contained within the abdomen in males
• Small penis in males
• Infertility

5. 3-Beta-Hydroxysteroid Dehydrogenase Deficiency

People with 3-beta-hydroxysteroid dehydrogenase deficiency have difficulty making all steroid hormones.

This form of CAH is very rare, with only about 60 people reported to have this condition.

Cause of 3-Beta-Hydroxysteroid Dehydrogenase Deficiency

The enzyme 3-beta-hydroxysteroid dehydrogenase is found in the adrenal glands and gonads and helps make hormones such as cortisol, aldosterone, testosterone, and estrogen.

Symptoms of 3-Beta-Hydroxysteroid Dehydrogenase Deficiency

MedlinePlus also states that people with 3-beta-hydroxysteroid dehydrogenase deficiency may have the following symptoms:

• Dehydration
• Poor feeding in infants
• Vomiting
• Irregular menstruation in females
• Early development of pubic hair in females
• Excessive body hair growth in females
• Atypical male genitalia
• Ambiguous genitalia in males
• Infertility in males and females

6. P450 Oxidoreductase Deficiency

P450 oxidoreductase deficiency (PORD) is a rare form of CAH, with about 100 reported cases of the disease. However, PORD is often mistaken for other types of CAH, so more people may be living with PORD. Researchers think that PORD may be the second most common cause of CAH in some populations, including people in Korea and Japan.

PORD is also known as “Antley-Bixler syndrome.”

Cause of PORD

PORD is caused by a change in an enzyme called P450 oxidoreductase. This enzyme plays an important role in making steroid hormones.

Symptoms of PORD

The symptoms of PORD can range from mild to severe. Mild PORD symptoms may include:

• Lack of menstruation by age 16
• Infertility
• Polycystic ovary syndrome (PCOS) — A hormone disorder that causes irregular menstruation, excess body hair, acne, and weight gain

People with moderate PORD symptoms may have ambiguous genitalia and infertility.

Severe PORD can cause symptoms such as:

• Abnormal formation of the bones in the skull
• Joint deformities
• Unusually long and slender fingers
• Bowing of the thigh bones
• Intellectual disability
• Delayed development

7. Lipoid Congenital Adrenal Hyperplasia

Lipoid CAH is the rarest and most severe form of CAH.

Causes of Lipoid CAH

Lipoid CAH is caused by a defect in the enzyme that converts cholesterol into pregnenolone — the building block for all steroid hormones made by the adrenal gland and gonads.

Symptoms of Lipoid CAH

Lipoid CAH is fatal in up to 2 out of 3 infants with the disease. Infants with lipoid CAH can have symptoms that appear soon after birth, including:

• Vomiting
• Diarrhea
• Dehydration
• Low sodium levels in the blood
• High potassium levels in the blood

According to Wolters Kluwer UpToDate, a website that doctors use to get current information on medical conditions, lipoid CAH can affect the appearance of the genitals. Males usually have external genitalia that appear female. Females usually have normally developed external genitalia.

Each type of CAH needs special medical care to manage hormone levels and overall health. It’s important to stay informed and work with your doctor for the best treatment.

Talk With Others Who Understand

On CAHteam, the site for people with congenital adrenal hyperplasia and their loved ones, people come together to gain a new understanding of CAH and share their stories with others who understand life with the condition.

What type of CAH do you have? Are you living with a rare type of CAH? Share your experience in the comments below.