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Hormones are tiny chemical messengers that help the body grow, develop, and stay balanced. They influence growth, energy levels, stress response, and more. In congenital adrenal hyperplasia (CAH), the adrenal glands — two small organs located above the kidneys — don’t make certain hormones the way they should. This can lead to a range of health concerns that may start early in life and continue over time.
There are several types of CAH, but more than 95 percent of people with CAH have the 21-hydroxylase deficiency type. This type can be classic or nonclassic, depending on how the genetic mutation (change) affects hormone production. Classic CAH is more severe and is usually diagnosed at birth. Nonclassic CAH is milder and may not be recognized until childhood, the teen years, or even adulthood.
In this article, we’ll break down the main differences between classic and nonclassic 21-hydroxylase deficiency CAH. You’ll learn what causes each form, what symptoms to look for, and how they’re diagnosed and treated.
Most cases of classic CAH happen when the body is missing an enzyme called 21-hydroxylase. The adrenal glands need this enzyme to make cortisol. Cortisol helps the body manage stress, blood glucose (sugar), and blood pressure.
Many children with CAH also can’t make enough aldosterone. This hormone is in charge of balancing sodium (salt) and water levels throughout the body. When aldosterone is very low, the body loses too much sodium through the urine. At the same time, the adrenal glands produce too many androgens (male sex hormones), which affect growth, puberty, and fertility.
The classic subtype is the most serious form of the condition and is almost always diagnosed in newborns or young infants. In many countries, including the United States, babies are screened for it through newborn screening. So, families are often aware of the condition right away.
While most CAH cases involve 21-hydroxylase deficiency, a less common form results from a deficiency in 11-beta-hydroxylase. This form often leads to excess androgens, early puberty, and hypertension (high blood pressure) in children.
There are two subtypes of classic 21-hydroxylase deficiency CAH: salt-wasting and simple-virilizing.
The salt-wasting type is more common and more severe. About 75 percent of people with classic CAH have this type. The adrenal glands can’t make enough aldosterone, causing dangerous salt loss, dehydration, and hypotension (low blood pressure).
The simple virilizing type is less severe and affects about 25 percent of people with classic CAH. Aldosterone production is usually enough to avoid a life-threatening salt-wasting crisis. However, cortisol is still low, and androgen levels are high. This can lead to atypical changes in sexual development and rapid growth.
Nonclassic CAH is the milder form. Unlike classic CAH, it’s not usually diagnosed in babies. Instead, it may be diagnosed later during childhood, adolescence, or even adulthood. Since it develops more slowly and can mimic other health problems, it may take years for people to receive the proper diagnosis.
Nonclassic CAH is also caused by abnormal changes in the 21-hydroxylase enzyme. However, unlike in classic CAH, the enzyme still partly works. So, the adrenal glands can usually make enough cortisol and aldosterone for basic needs. The main issue is an excess of androgens, which is what causes most of the symptoms. Nonclassic CAH is usually not life-threatening.
Between these two conditions, symptoms can vary greatly.
The signs and symptoms of classic CAH are usually a result of too much androgen production in the body. According to Cleveland Clinic, symptoms for both the salt-wasting and simple-virilizing forms can include:
People with the salt-wasting form of classic CAH may have additional adrenal symptoms, such as salt craving due to low salt levels, dehydration, and vomiting.
Nonclassic CAH doesn’t usually cause problems in newborns. Symptoms tend to appear later in life and may vary from person to person. For some people living with nonclassic CAH, the symptoms may be so mild that they don’t even know they have it.
If symptoms do appear, they may include:
One of the biggest differences between classic and nonclassic CAH is when and how the diagnosis is made.
Classic CAH is typically found right after birth with a newborn screening. This happens with a small blood sample to check the baby’s hormone levels. If results are abnormal, doctors may order more lab tests or genetic testing to confirm the diagnosis.
Because symptoms of classic CAH can become dangerous very quickly, early diagnosis is critical for prompt treatment and survival. Prenatal (before birth) genetic screening is also available and is usually utilized for individuals who are pregnant and already have a child with CAH.
Nonclassic CAH isn’t typically detected in routine newborn screening because the enzyme activity is sufficient to maintain near-normal hormone levels in early life. Instead, it may be suspected later when unusual symptoms start to appear, such as rapid growth, irregular periods, or excess body hair.
Diagnosing nonclassic CAH includes:
Another common test is the adrenocorticotropic hormone (ACTH) stimulation test, used in the diagnosis of both classic and nonclassic CAH. In this test, a person is given a small dose of ACTH — a hormone that tells the adrenal glands to release cortisol. Blood samples taken before and after the dose show how well the adrenal glands respond. Cortisol production is often lower than expected, while levels of a hormone called 17-hydroxyprogesterone (17-OHP) rise sharply.
For both classic and nonclassic forms of CAH, the goal of treatment is to lower excess androgens and prevent complications.
Classic CAH always requires treatment. To replace cortisol, most people take glucocorticoids, such as:
If the adrenal glands also can’t make enough aldosterone, mineralocorticoids like fludrocortisone are added to help the body retain salt and water. Infants with the salt-wasting form of classic CAH may also need to take extra salt supplements.
During illness, injury, or surgery, the body needs more cortisol than usual. So, extra doses of medicine may need to be added to prevent an adrenal crisis. This is a sudden and life-threatening emergency where the body doesn’t make enough cortisol. Without prompt treatment, it can lead to severe dehydration, dangerously low blood pressure, and shock.
For female infants with classic CAH who have atypical genitalia, reconstructive surgery may be considered, according to Cleveland Clinic. Some parents may choose to wait until their child is old enough to weigh in on this decision.
Health experts recommend that people with classic CAH wear a medical identification bracelet or necklace at all times. This helps medical professionals and first responders know what to do in case of a medical emergency.
Treatment for nonclassic CAH is more flexible. Some people may never need medicine if symptoms are mild. When treatment is needed, the most common option is low-dose glucocorticoids to reduce androgen levels. Anti-androgens are another treatment option that may be recommended.
For those with irregular periods, excess body hair, or acne, oral contraceptives (birth control pills) or other hormone medicines may help. People with fertility challenges may benefit from specialized fertility treatments. Because nonclassic CAH is not life-threatening, the main focus of treatment is managing symptoms and improving quality of life.
On CAHteam, people share their experiences with congenital adrenal hyperplasia, get advice, and find support from others who understand.
Are you living with classic or nonclassic CAH? Let others know in the comments below.
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