Congenital adrenal hyperplasia

Congenital adrenal hyperplasia (also called CAH) is a disorder caused by hormone problems. Hormones are chemicals made by the body. Babies with CAH have trouble making enough of certain hormones and make too much of other hormones.

All babies are tested for CAH as part of newborn screening after birth. About 1 in 25,000 babies is born in the United States each year with CAH.

CAH can affect how a baby’s genitals (sex organs) develop. This can cause a baby girl’s genitals to look like a baby boy’s. It also can cause a boy or girl to start puberty at a young age. Puberty is the time in your life when your body develops and changes from being a child to an adult.

One kind of CAH called salt-wasting CAH can cause the body to have low blood pressure or to lose too much salt. If not treated, this condition can cause death. This is why newborn screening right after birth is so important.

What causes CAH?

CAH is inherited. This means it’s passed from parent to child through genes. Genes are parts of your body’s cells that store instructions for the way your body grows and works. In the United States, all babies have newborn screening tests to see if they may have certain inherited conditions, including CAH, when they’re born.

Sometimes the instructions in genes change. This is called a gene change or a mutation. Parents can pass gene changes to their children. Sometimes a gene change can cause a gene to not work correctly. Sometimes it can cause birth defects or other health conditions. A birth defect is a health condition that is present in a baby at birth.

For a baby to have CAH, both parents either have CAH themselves or they are both CAH carriers. A CAH carrier has the gene change for CAH, but doesn’t have CAH. Parents of babies with CAH usually don’t have CAH themselves. But if both parents are CAH carriers, each of their children has a 25-percent (1 in 4) chance of being born with CAH.

A genetic counselor is a person who is trained to help you understand about how genes, birth defects and other medical conditions run in families, and how they can affect your health and your baby’s health. You may want to talk with a genetic counselor about CAH if:

  • You or your partner has a family history of CAH. Family history means that the condition runs in your family.
  • You or your partner want to find out if you’re a CAH carrier. Both of you can get tested to find out if you’re a CAH carrier.
  • You already have another child with CAH.

Your provider may be able to diagnose CAH before birth using these tests:

  • Amniocentesis (also called amnio). This is a test that takes some amniotic fluid from around your baby in the uterus (womb). The test checks for birth defects and genetic conditions in your baby. You can get this test at 15 to 20 weeks of pregnancy.
  • Chorionic villus sampling (also called CVS). This is a test that checks tissue from the placenta to see if a baby has a genetic condition, like CAH. The placenta grows in your uterus and supplies the baby with food and oxygen through the umbilical cord. You can get CVS at 10 to 13 weeks of pregnancy.

If these tests show that your baby has CAH, your provider may start treatment before birth. This may lower your baby’s chances of having some problems from CAH. For example, some health care providers recommend a medicine called dexamethasone. If you’re pregnant with a baby girl who has CAH, taking dexamethasone during pregnancy may help your baby’s genitals develop normally. If you’re pregnant with a baby boy who has CAH, taking dexamethasone during pregnancy may help his adrenal glands work properly.

Providers don’t really know if dexamethasone has any long-term health effects on children with CAH, so some don’t recommend this treatment. Dexamethasone also may cause side effects in pregnant women, like gaining a lot of weight, having mood swings and having high blood pressure. Talk to your provider before taking dexamethasone during pregnancy to make sure it’s right for you and your baby.

What are the different kinds of CAH?

There are two main kinds of CAH:

  1. Classic CAH. This is the most common kind. It causes a baby’s body to make large amounts of androgens before birth. Androgens are male sex hormones. They help a baby boy’s body develop sex organs. Later in life, they help boys grow and go through puberty. Girls have androgens, too, but not as much as boys. Too much androgens can cause health problems in both boys and girls.
  2. Nonclassic CAH. Babies with this kind of CAH are healthy when they’re born. But they may have signs and symptoms of CAH later in life.

There are two kinds of classic CAH:

  1. Salt-wasting. Three in 4 babies (75 percent) with classic CAH have this type. Salt-wasting CAH happens when a baby’s body makes too much androgen but not enough cortisol and aldosterone. Cortisol is a hormone that keeps blood sugar levels normal. It also helps the body handle illness and infection. Aldosterone is a hormone that helps salt and water levels stay normal in the blood to help keep blood pressure at a healthy level. Without treatment, salt-wasting CAH can lead to dehydration and death. Dehydration means not having enough water in your body.
  2. Simple virilizing. Babies with this kind of CAH make the right amount of aldosterone, but they make too little cortisol and too much androgen. These babies also may have high blood pressure.

How do you know if your baby has CAH?

Babies with salt-wasting CAH may show these signs and symptoms in the first weeks after birth:

  • Dehydration. Your baby may be dehydrated if he doesn’t make tears, goes more than 6 hours without a wet diaper, has dark urine or is really sleepy or fussy.
  • Throwing up
  • Trouble feeding
  • Weight loss
  • Diarrhea

If a baby with salt-wasting CAH gets too dehydrated and her blood pressure drops too low, she may be at risk for shock. Shock is when body organs don’t get enough blood flow. If not treated, babies in shock can die. Symptoms of shock caused by CAH include having a fast pulse or being really fussy or unconscious.

Babies with salt-wasting CAH as well as babies with simple virilizing CAH may have these signs and symptoms:

  • Girls may have genitals that look like boy genitals or that look both male and female. These are called ambiguous genitals.
  • Boys may not show symptoms at birth. But with careful examination, some may appear to have more mature genitals for their age. If they don’t show signs at birth, they can show signs of puberty as early as 2 to 3 years of age. These signs can include having a deep voice, an enlarged penis or smaller-than-normal testicles.

How is CAH treated?

Early and lifelong treatment can help lessen the effects of CAH for your baby. If your baby has classic CAH, her health care provider may work with a pediatric endocrinologist. This is a doctor who treats children with hormone problems.

Your baby’s treatment may include:

  • A meal plan. If your child has salt-wasting CAH, she may need to get more salt from foods than healthy people. She may need to take salt tablets to keep her from getting dehydrated. Her provider tells you how much salt your child needs.
  • Medicine. Some children with CAH may need to take a hydrocortisone pill. This is a man-made form of cortisol. If your child has CAH and goes through puberty at a young age, he may need to take medicines that lower androgen levels. Babies and children with salt-wasting CAH may need to take a Florinef pill. This medicine helps make up for missing aldosterone in your child’s body and helps treat his salt-wasting CAH.
  • Surgery. In some cases, a girl with CAH may have surgery at birth or later in life to make her genitals look like a girl’s genitals.

See also: Newborn screening

Last reviewed: January, 2014