General Condition Information
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- Hundreds of babies are born every year in the United States with the common form of this condition. Overall, 1 out of every 14,000 to 18,000 babies is born with this condition.
- It is more common in babies of Yupik or Alaskan Eskimo descent, and less common in babies of African American and Asian descent.
- Visit GeneReviews to learn more about how often this condition occurs.
What is Congenital adrenal hyperplasia
Congenital adrenal hyperplasia (CAH) is a group of inherited (genetic) conditions that can change the way your baby’s body develops and responds to stress.
Adrenal glands are small organs that produce hormones. These hormones help your body respond to illness, determine levels of salt and water in your body, and direct development of the genitals.
In CAH, certain enzymes inside the adrenal glands do not work properly. Without working enzymes, the adrenal glands do not make enough of the hormones the body needs. The adrenal glands also grow very large. The name congenital adrenal hyperplasia is given because the condition is present from birth (congenital), it affects the adrenal glands, and it makes the glands large (hyperplasia).
The form of CAH your baby has depends on which enzyme is not working. In the most common form of CAH, the enzyme 21-hydroxylase is not able to make enough of hormones called cortisol and aldosterone. This version is called CAH due to 21-hydroxylase deficiency (21-OHD).
Cortisol is important for keeping blood sugar levels normal and for protecting the body during stress. Aldosterone is important for maintaining normal salt (sodium) levels in the body.
When 21-hydroxylase is not working, pieces that should be made into cortisol and aldosterone are turned into androgens instead. Androgens are male hormones, like testosterone, which are responsible for the development of traits typically seen in men.
The two main types of CAH due to 21-OHD are:
- Classic CAH
- Nonclassic CAH
Classic CAH is further broken down into two forms, known as the salt-wasting form and the simple-virilizing form. The type of CAH depends on how well 21-hydroxylase can make cortisol and aldosterone and prevent androgens from building up.
Classic CAH is the most severe form. Most babies with classic CAH have the salt-wasting form, where very little cortisol and aldosterone are made. Babies with the simple-virilizing form of classic CAH also make very little cortisol but do make some aldosterone.
Nonclassic CAH is the mildest form. The two classic forms of CAH due to 21-OHD are the forms that newborn screening assesses.
High levels of androgens, low levels of aldosterone, and low levels of cortisol can lead to the signs and symptoms of classic CAH due to 12-OHD.
There are other forms of CAH that are very rare, including:
- CAH due to 11-beta-hydroxylase deficiency
- 17 alpha-hydroxylase/17,20-lyase deficiency
- 3-beta-hydroxysteroid dehydrogenase deficiency
- Cytochrome P450 oxidoreductase deficiency
These conditions also cause a hormone imbalance due to a certain enzyme in the adrenal glands not working properly. Because these versions are not often detected by newborn screening, this page only refers to classic CAH due to 21-OHD.
Newborn Screening and Follow-Up
Newborn screening for CAH is done using a small amount of blood collected from your baby’s heel. To learn more about this process, visit the Blood Spot Screening page.
During screening, a special machine measures how much of a certain substance (called 17-OHP) is in your baby’s blood. This is a substance that builds up when the body does not produce enough cortisol. Babies with high levels of 17-OHP might have CAH due to 21-OHD.
If your baby’s blood spot screening result for 17-OHP is out-of-range, your baby’s health care provider will contact you. Together, you will discuss next steps and follow-up plans.
An out-of-range screening result does not mean that your baby definitely has the condition. It does mean that your baby needs more follow-up testing. To learn more about screening results, visit the Blood Spot Screening Results page.
Your baby may need the following tests after an out-of-range screening result:
- Blood and/or urine tests
- Genetic testing (usually a blood sample)
You should complete any recommended follow-up testing as soon as possible. Babies with this condition can have serious health problems soon after birth if they are not diagnosed and treated quickly.
False-positive newborn screening results for this condition do happen. Some situations can affect screening results for CAH:
- Screening samples were collected too early (before the baby is 24 hours old)
- Babies who were born early (premature), had a low birth weight, or were ill
False-negative results for CAH can be seen in babies whose mothers were given steroids like prednisone or dexamethasone. They can also be seen in babies whose 17-OHP levels don’t rise until a few weeks after the newborn screening sample is collected.
Newborn screening helps babies lead healthier lives. If your baby has an out-of-range result, follow up with your health care provider quickly. It is important to follow their instructions. Your baby may need to get treatment right away, even if they are not showing signs or symptoms. In some cases, your baby’s health care provider may decide it is best to watch (monitor) your baby to decide next steps. Careful monitoring and early treatment will help your baby stay as healthy as possible.
Signs of CAH may be apparent at birth, appear very shortly after birth (a few days to weeks of life), or appear later in childhood.
Signs of classic salt-wasting CAH may include:
- Male-like genitals in girls
- Poor feeding
- Sleeping longer or more often (lethargy)
- Weight loss or failure to gain weight normally
- Gets upset easily (irritability)
- Rapid heart rate
Signs of the classic simple-virilizing form of CAH can include:
- Early onset of body hair
- Male-like genitals in girls
- Small testicles in boys
- Large penis in boys
Nonclassic CAH typically does not have the signs and symptoms listed above, but it can cause early-onset body hair and abnormal periods in childhood and teenage years.
There are several types of CAH. The type of CAH that is detected by newborn screening is caused by a change in the CYP21A2 gene. This gene gives your body instructions for making the enzyme 21-hydroxylase that produces cortisol and aldosterone.
Without a working CYP21A2 gene, 21-hydroxylase cannot make enough cortisol and aldosterone in your baby’s body. Androgens build up in their body. This hormone imbalance can damage the body and change the way it develops.
- CAH is an autosomal recessive condition. Babies inherit the condition when each parent passes down a nonworking CYP21A2 gene to their baby. Only babies with two nonworking CYP21A2 genes—one from the mom and one from the dad—have this condition.
- People with one working copy and one nonworking copy of the CYP21A2 gene are called carriers.
- Carriers do not have or develop the condition. However, they may pass down a nonworking copy of the gene to their children.
- If two parents are carriers of a nonworking copy of the CYP21A2 gene, they have a 1 in 4 chance of having a child with CAH.
- Carriers for CAH often do not know they are carriers before having a child with the condition. In most cases, families have no history of the condition until the birth of a child with CAH.
- Parents who already have a child with CAH due to a change in the CYP21A2 gene still have a 1 in 4 chance of having another child with CAH. This 1 in 4 chance stays the same for all future children.
- Genetic counselors and medical geneticists can help families learn about this condition and the chance of having children with it. Visit the National Society of Genetic Counselors to find a genetic counselor and the American College of Medical Genetics and Genomics to find a medical geneticist.
Treatment and Management
It is important to talk to your health care provider about which treatment(s) are best for your baby. The goal of treatment is to prevent the health problems caused by this condition.
Treatments may include the following:
- Hydrocortisone to replace the missing cortisol
- Fludrocortisone to maintain proper salt and fluid levels (in the salt-wasting form)
- Salt (sodium chloride)
- Surgery may be considered in some females with genital or urinary problems
Children who receive early and ongoing treatment for CAH can have healthy growth and development. However, children may not grow to be as tall as expected.