Congenital Adrenal Hyperplasia

National Organization for Rare Disorders, Inc.

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  • CAH
  • adrenogenital syndrome

Disorder Subdivisions

  • None

General Discussion

Congenital adrenal hyperplasia (CAH) is a group of rare autosomal recessive disorders characterized by a deficiency of one of the enzymes needed to make specific hormones. CAH effects the adrenal glands located at the top of each kidney. Normally, the adrenal glands are responsible for producing three different hormones: corticosteroids, which gage the body's response to illness or injury, mineralocorticoids, which regulate salt and water levels, and androgens, which are male sex hormones. An enzyme deficiency will make the body unable to produce one or more of these hormones, which will result in the overproduction of another in order to compensate for the loss.

The most common cause of CAH is the absence of the enzyme 21-hydroxylase. Different mutations in the gene responsible for 21-hydroxylase result in different levels of the enzyme. and produce a spectrum of effects. CAH due to 21-hydroxylase deficiency is responsible for 95% of all cases of CAH and is broken down further into two subcategories: classical CAH, which can be divided further into the salt-losing form or the simple-virilizing form, and non-classical CAH. Classical CAH is by far the more severe form and can result in adrenal crisis and death if not detected and treated. Non-classical CAH is milder, and may or may not present symptoms. Since the absence of 21-hydroxylase makes these individuals unable to make the hormone cortisol and, in the case of salt-losing CAH, aldosterone, the body produces more androgens which cause a variety of symptoms such as abnormal sexual development.

There are other much rarer forms of CAH as well, including 11-Beta hydroxylase deficiency, 17a-hydroxylase deficiency, 3-Beta-hydroxysteroid dehydrogenase deficiency, and congenital lipoid adrenal hyperplasia, which all present different symptoms.

Although CAH is not curable, as long as patients receive adequate care and treatment, they can go on to lead normal lives.


Many individuals with CAH present with abnormally enlarged adrenal glands (hyperplastic adrenomegaly) that produce excessive amounts of androgens (male steroid hormones) leading to abnormal sexual development in females affected with the disease. Females with severe or classic virilizing CAH due to 21-hydroxylase deficiency will most likely have ambiguous external genitalia (masculinization or virilization), although they are genetically female and will have normal internal reproductive organs. Males with this type of CAH will not have ambiguous genitalia. Both genders can experience other symptoms such as early onset of puberty, fast body growth, and premature completion of growth leading to short stature, if they are not diagnosed and treated in early life.

About 75% of people with classical CAH due to 21-hydroxylase deficiency also have a deficiency of the hormone aldosterone, leading to the inability to retain salt and water (salt wasting). This results in excessive loss of water (dehydration), low circulating blood volume (hypovolemia), and abnormally low blood pressure (hypotension and shock). Without treatment, this severe form of CAH can lead to profound weakness, vomiting, diarrhea, and circulatory collapse due to adrenal crisis in infancy. The remaining 25% are referred to as simple-virilizers and do not have a problem regulating salt and water levels.

Fortunately in the United States, and in many other developed countries, there is universal newborn screening for CAH due to 21-hydroxylase deficiency, and the vast majority of children are diagnosed and treated early to avoid these complications.

The mild form of 21-hydroxylase deficiency (non-classical CAH) is not life-threatening and is due to a more common genetic mutation. This mild form is not usually detected in our newborn screening programs, and it seldom requires early treatment. Symptoms in later childhood may include premature body hair or acne development. In adolescent females, the most common problems include excessive facial or body hair, menstrual irregularities, and pustular acne. Both genders have normal genitals. A small proportion of the non-classic CAH population has sub-fertility. Patients with CAH may or may not require treatment to improve their quality of life.

Rare forms of CAH:

11-Beta hydroxylase deficiency patients are protected from the symptoms associated with adrenal crisis, although they are subject to others such as hypertension due to salt retention and ambiguous genitalia in females.

17a-hydroxylase deficiency also results in ambiguous external genitalia in males and lack of a pubertal development or menstrual cycles (amenorrhea) in females.

3-Beta-hydroxysteroid dehydrogenase deficiency leads to ambiguous genitalia in males and females. In both genders it can lead to salt-wasting.

Lastly, congenital lipoid adrenal hyperplasia may cause early death due to adrenal crisis. Males have ambiguous genitalia. Both males and females, if they survive, would likely be infertile.


Deletions and mutations in the CYP21A2 gene account for all cases of the 21-hydroxylase deficiency form of CAH. Mutations in the CYP11B1, CYP17A1, HSD3B2 and STAR genes are responsible, respectively, for 11-hydroxylase, 17-hydroxylase, 3-beta-hydroxysteroid dehydrogenase deficiencies, and lipoid adrenal hyperplasia, the other rarer forms of CAH. An additional form of CAH has recently been described called P450 oxidoreductase deficiency. This is caused by lack of a co-factor necessary for the activity of several of the above enzymes, and has a variable presentation. Some cases have been associated with skeletal malformations (one type of Antley-Bixler syndrome).

All forms of CAH are inherited as an autosomal recessive genetic trait. Recessive genetic disorders occur when an individual inherits two copies of an abnormal gene for the same trait, one from each parent. If an individual receives one normal gene and one gene for the disease, the person will be a carrier for the disease but usually will not show symptoms. The risk for two carrier parents to both pass the defective gene and have an affected child is 25% with each pregnancy. The risk to have a child who is a carrier like the parents is 50% with each pregnancy. The chance for a child to receive normal genes from both parents and be genetically normal for that particular trait is 25%. The risk is the same for males and females.

Parents who are close relatives (consanguineous) have a higher chance than unrelated parents to both carry the same abnormal gene, which increases the risk to have children with a recessive genetic disorder.

Affected Populations

The most common form of CAH, 21 hydroxylase deficiency, affects approximately 1:10,000 to 1:15,000 people in the United States and Europe. Among the Yupik Eskimo, the occurrence of the salt-wasting form of this disorder may be as high as 1 in 282 individuals. Other forms of CAH are much rarer.

Based on small population surveys, non-classical CAH affects approximately 1 in 30 Ashkenazi Jews, 1 in 40 Hispanics, 1 in 50 Yugoslavians, and 1 in 300 Italians. Thus far, about 1 in 100 individuals in the Caucasian non-Jewish groups who have been studied have the non-classical form of this disorder.

Standard Therapies


All newborns in the United States are screened for 21-hydroxylase deficiency. Non-classic CAH is frequently not detected in the newborn test and therefore, may not be diagnosed until childhood or early adulthood when the patient first starts showing symptoms. Genetic testing for the gene mutations associated with the various forms of CAH is available, but is most often performed when pre-pregnancy genetic counseling is indicated, after an endocrinologist confirms the diagnosis through blood hormone tests, or if results of hormone tests are not definitive.

Prenatal diagnosis is available for couples at risk for having a child affected with CAH using first trimester chorionic villus sampling and testing the fetal DNA for a particular CAH gene mutation known to occur in the family.

Clinical Evaluation

If CAH is detected in a fetus, prenatal treatment is a possibility, although it should be regarded as experimental. The oral drug dexamethasone can be given to pregnant women in a subsequent pregnancy if she has given birth to child with severe classical CAH. Such treatment does not prevent or cure the disease, but may lessen the virilization of affected female fetuses. There is limited knowledge about the long-term safety of this procedure, and this should be done only under the supervision of experienced clinicians who report to an ethical review board for human studies.

Monitoring hormones levels in individuals with CAH is crucial throughout their post-natal life. Height and weight are other important aspects that need to be monitored in order to know if treatment should be adjusted, particularly in children. Monitoring bone age is an additional tool to determine if the child is undergoing proper physical maturation. A simple x-ray of the hand can show the growth centers and provide an estimate of predicted adult height. As individuals mature, the growth centers change and have characteristic appearances at different ages. Too much sex hormone secretion can cause bones to age more rapidly, and treatment can slow this progression, if caught early.


Treatment of CAH varies greatly depending on the type and severity. CAH cannot be cured, but it can be effectively treated. Treatment of classical CAH starts soon after birth and is needed throughout the patient's life. People with classical CAH should have a team of healthcare providers, including specialists in pediatric endocrinology, uro-gynecologic surgery (for girls), psychology and genetics. People with classical CAH can have normal, fulfilling lives. Patients with non-classical CAH may not need any treatment, depending on their symptoms. Treatment must be individualized by doctors who have experience with this condition.

The primary goal of treating classical CAH is to reduce the excess androgen production and replace the deficient hormones. Proper treatment with the correct dosage of these hormones is crucial to preventing adrenal crisis and virilization. Daily tablets including glucocorticoids (to replace cortisol), mineralocorticoids (to replace aldosterone) and salt supplements may be prescribed, particularly in infancy. During times of high stress or illness adrenal glands are normally much more active. Therefore, when ill or after major surgery or stressful event, CAH patients must be closely monitored because their bodies will require more hormones to help the body recover and meet increased demands. During adulthood, individuals with CAH usually require fewer hormones than during childhood and puberty. Hormone levels need to be adjusted and monitored throughout the patient's life. The dose of glucocorticoids should be minimized to avoid development of Cushing's syndrome, a disorder characterized by a variety of symptoms and physical abnormalities including weight gain; skin, muscle and bone changes.

Female classical CAH patients also have the option of surgery to correct the appearance of ambiguous genitalia. Usually surgery is thought to be easier when performed within 2-6 months after birth. The choice to have the surgery should be reserved for infants with severe genital ambiguity, and is most often a joint decision of the parents and medical-surgical teams. Some parents choose to wait until their daughter is old enough to have a say in her surgery. Others feel the problem is severe and should be corrected immediately. If this is the case, finding a highly skilled pediatric urologic surgeon is of the utmost importance. This type of surgery has seen a great deal of improvement in terms of cosmetic appearance and functionality over the past few years. It is also highly recommended that families of girls who undergo this surgery have the option to receive psychological care.

Non-classical CAH on the other hand, is not life-threatening and relatively mild. People who have no obvious symptoms of non-classical CAH do not require surgery or treatment. If a patient with non-classical CAH begins to enter puberty too early, has early maturation of bones, or is female yet develops masculine features, glucocorticoids are recommended. Fertility problems can also be corrected with glucocorticoids and/or fertility drugs. Women who do not wish to conceive may also be prescribed oral contraceptives. Unlike severe forms of CAH, non-classical CAH patients are free to taper and stop treatment when symptoms go away.

Please refer to the Endocrine Society Clinical Practice Guidelines for additional information regarding diagnosis and treatment of CAH.

Investigational Therapies

Information on current clinical trials is posted on the Internet at All studies receiving U.S. Government funding, and some supported by private industry, are posted on this government web site.

For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:

Tollfree: (800) 411-1222

TTY: (866) 411-1010


For information about clinical trials sponsored by private sources, contact:



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Speiser PW, Azziz R, Baskin LS, Ghizzoni L, Hensle TW, Merke DP, Meyer-Bahlburg HF, Miller WL, Montori VM, Oberfield SE, Ritzen M, White PC; Endocrine Society. Congenital adrenal hyperplasia due to steroid 21-hydroxylase deficiency: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab. 2010;95(9):4133-60.

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CARES Foundation. Accessed on: January 16, 2012.

Hormone Foundation. Accessed on:January 16, 2012.

Donohoue PA, Parker KL, Migeon CJ. Congenital adrenal hyperplasia. In: Scriver CR, Beaudet AL, Sly WS, Valle D, Vogelstein B, eds. The Metabolic and Molecular Bases of Inherited Disease (OMMBID). Chap 159. New York, NY: McGraw-Hill. Available at Accessed on:January 18, 2012.

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CLIMB (Children Living with Inherited Metabolic Diseases)

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MAGIC Foundation

6645 W. North Avenue

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Tel: (708)383-0808

Fax: (708)383-0899

Tel: (800)362-4423



National Adrenal Diseases Foundation

505 Northern Bloulevard

Great Neck, NY 11021


Tel: (516)487-4992

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March of Dimes Birth Defects Foundation

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Tel: (914)997-4488

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Ambiguous Genitalia Support Network

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Tel: (209)727-0313

Child Growth Foundation

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NIH/National Institute of Child Health and Human Development

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CARES Foundation, Inc.

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Tel: (908)364-0272

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Hormone Health Network Endocrine Society

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Tel: (202)971-3636

Fax: (202)736-9705

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Congenital Adrenal Hyperplasia Education and Support Network

19724 East Pine #149

Catossa, OK 74015


Tel: (918)604-4039



Genetic and Rare Diseases (GARD) Information Center

PO Box 8126

Gaithersburg, MD 20898-8126

Tel: (301)251-4925

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CAH (Congenital Adrenal Hyperplasia) Support Group

2 Windrush Close


Bedfordshire, MK45 1PX

United Kingdom

Tel: 08006523181

Tel: 08006523181



Madisons Foundation

PO Box 241956

Los Angeles, CA 90024

Tel: (310)264-0826

Fax: (310)264-4766



Congenital Adrenal Hyperplasia Support Group

PO Box 66


Hauraki, 3641

New Zealand

Tel: 6433584507

Fax: 6433584506

Tel: 0800224698



Accord Alliance

531 Route 22 East #244

Whitehouse Station, NJ 08889


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