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Congenital Adrenal Hyperplasia (CAH)

What is Congenital Adrenal Hyperplasia (CAH)?
Congenital Adrenal Hyperplasia (CAH) is a medical condition that has different types.  The most common type—90% of cases of CAH—is called 21-hydroxylase deficiency. Parents most often find out that their baby has CAH from newborn screening.  CAH occurs when the adrenal glands are unable to produce hormones normally, leading to a hormone imbalance.  CAH can be life threatening if not properly treated.  adrenal glands located atop the kidneys

What these big words mean:

What causes CAH? 
CAH is caused by not having enough of an enzyme (most commonly 21-hydroxylase) that the adrenal glands need to work right. The adrenal glands are part of the endocrine system.  The adrenal glands make hormones, chemical “messengers” that the body needs to function well. In CAH, the adrenal glands make too little of certain hormones. These hormones are cortisol and aldosterone

When the adrenal glands make too little cortisol and aldosterone, it can endanger the child’s life. But by replacing hormones through medical treatment, a child will be able to develop normally and be healthy.
In 21-OH CAH, when the adrenal glands try to make cortisol and aldosterone, they instead make more of other hormones: androgensAndrogens are another group of hormones involved in CAH. Both males and females make androgens, but males make more. Having too much androgen affects how girls’ bodies develop, even before they are born.

What are the different types of CAH?  

How is CAH inherited?
Parents can be carriers of the gene that causes CAH without being affected themselves. If both parents are carriers of the gene that leads to CAH, they can pass it to their child.  If both parents pass the gene to the child, the child will have CAH.  There is a 25% chance that the child of two unaffected carriers will have CAH.  This type of inheritance is called autosomal recessive. If you have a child with CAH or you have CAH in your family, it’s a good idea to seek genetic counseling that can help you and your relatives with family planning.

How common is it?  
About one in 15,000 children is born with the classic form of CAH each year in the United States. CAH occurs equally in boys and girls.  Non-classic or late-onset CAH is one of the more common genetic conditions.  It may affect one to five percent of people in a given community, varying by the racial and ethnic makeup.  It is more common in certain ethnic groups.


Image of the adrenal glands reproduced courtesy of the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), NIH, DHHS;

Written and compiled by Kyla Boyse, RN and Talyah Sands.  Reviewed by David E. Sandberg, Ph.D.

May 2011


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