What is CAH?

There’s lots to learn about Congenital Adrenal Hyperplasia (CAH), but there’s a lot of information out there too. On this page, you’ll find pictures, videos, articles and links to other resources to help you find out a little more about CAH.

CAH - a simple description

CAH (congenital adrenal hyperplasia) occurs approximately once in every 15,000 people worldwide. It is an inherited condition which prevents the adrenal glands functioning correctly. To stay healthy, people with CAH must take daily life-long medication to replace the hormones which their adrenal glands don’t make. People with CAH are at risk of a life-threatening adrenal crisis in an emergency, for instance if they are ill or injured. 


The adrenal glands sit above each kidney – one on each side of the body. Each adrenal gland is made up of the medulla (middle) and the adrenal cortex (outer). The medulla makes adrenaline, and this part works perfectly normally in CAH (congenital adrenal hyperplasia). The adrenal cortex is in three ‘layers’ and makes three main hormones from cholesterol – 1. corticosteroids, which regulate the body’s response to stress; 2. mineralocorticoids, which regulate salt and water levels; and 3. androgens, which are male sex hormones).

In CAH, an enzyme deficiency caused by a deleted or mutated gene prevents the adrenal gland from making enough of these hormones correctly.

In order to compensate for the low levels of these hormones, the pituitary gland makes ACTH which pushes the adrenal gland to work harder. The constant unsuccessful rise in these hormones causes the adrenal cortex to increase in size and become ‘hyperplastic’. This in turn, makes the adrenal cortex produce more androgens while corticosteroid and mineralocorticoid levels remain low.







The three mains steroids (or hormones) involved in CAH are Corticosteroids, Mineralocorticoids and Androgens.


Corticosteroids (Cortisol)

Controls how the body copes with emotional and physical stress, such as infection or injury. It also helps to control blood sugar levels, raising these levels if they become too low (particularly in children).




Mineralocorticoids (Aldosterone)

Helps to regulate the salt levels in the body. Aldosterone causes the kidneys to conserve salt if there is too little salt in the diet, or if a lot of salt is lost due to excessive sweating. Conversely, if a lot of salt is eaten, less Aldosterone is secreted, allowing the excess salt to be passed in the urine.



A group of male hormones, one of which is testosterone. Testosterone is produced by the adrenal cortex in both males and females controls the formation of pubic hair at the onset of puberty. Testosterone is also produced by the testis and in small amounts by the ovary.



Although there are many different grades of severity of CAH (congenital adrenal hyperplasia), there are three main types of CAH (over 90% of cases) which are caused by a deficiency of an enzyme called 21 hydroxylase. The three main types of CAH are ‘Salt-wasting’ (most cases), ‘Non-salt wasting’ and ‘late onset CAH’.

Another type of CAH is caused by a deficiency of the enzyme 11-beta hydroxylase and while deficiencies of other enzymes occur they are exceedingly rare. 

Over 90% of people with CAH have a deficiency of an enzyme called 21 hydroxylase.

The most common types of CAH – 21 hydroxylase deficiency

The three main types of CAH caused by a deficiency of the 21 hydroxylase enzyme are salt-wasting, non-salt wasting and late onset. In these forms of CAH the production of Cortisol and Aldosterone is low.

In salt-wasting CAH, the hormone aldosterone in completely lacking which results in uncontrolled loss of salt from the body through urine.

In non-salt wasting CAH, the salt balance is usually normal. However, in stressful situations, those with non-salt wasting CAH may begin to lose salt and hence require extra treatment.

In both ‘salt wasting’ and ‘non-salt wasting’ types of CAH, the salt loss can cause acute dehydration, very low blood pressure (hypotension) and vomiting. As salt (sodium and chloride) and sugar (glucose) levels fall in the blood, potassium levels rise and if left untreated, a potentially life-threatening Adrenal Crisis can result.

Untreated CAH, or illness in a person with CAH, can cause a potentially life-threatening Adrenal Crisis.

‘Salt wasting’ and ‘non-salt wasting’ CAH can cause differences in early sexual development due to the body producing excess testosterone to compensate for the low levels of cortisol and aldosterone. In boys, this excess of testosterone causes early sexual development. In females, the excess in testosterone can cause differences in sexual development before birth.

Only by correcting the levels of Cortisol with substitute therapy does the body recognise normal levels and stop producing excessive amounts of testosterone.

CAH can cause differences in sexual development due to the body producing excess testosterone to compensate for the low levels of cortisol and aldosterone.


The mildest form of CAH – Late onset CAH

Last onset CAH can affect men and women at any age. As with other forms of CAH, the body tries to correct the low levels of aldosterone and cortisol by producing excess testosterone.

For women, symptoms of unwanted hair growth or irregular periods can start at any time after puberty. Often treatment with steroids is not necessary in women with late onset CAH. Instead, giving oestrogen as in the oral contraceptive can regulate testosterone from the ovary. In fact, the treatment of late onset CAH is usually the same as for the polycystic ovary syndrome because the two conditions are so similar.

For men, late onset CAH usually goes unrecognised although it may cause the sperm count to be low.


11-beta hydroxylase deficiency and other enzyme deficiencies

These types of CAH are much rarer that 21 hydroxylase deficiency. Treatment of these types of CAH is more complicated because high blood pressure can be severe if treatment inadequate. The balance of treatment in 11-beta hydroxylase deficiency is very difficult and an experienced specialist is essential.

CAH CoMIC- A concise, medical information cine

 A 5-minute infographic/sketch style video that explains key aspects of CAH.

HealthSketch video – What is CAH?

A 5 minute video which explains key things about CAH using a sketch format – this video is also featured above and on our homepage.

Medikidz by Jumo Health – Understanding CAH

A 10-minute cartoon-syle video that explains the key points of CAH – very informative for all!

British Society for Paediatric Endocrinology & Diabetes  (BSPED)

BSPED aims to improve the care of children and young people with endocrine disorders and diabetes mellitus by bringing together professionals from a range of disciplines. Visit the ‘Clinical Resources’ section to find Patient Information about CAH.

CARES Foundation Resources (including translations to languages other than English)

Some useful resources from the CARES Foundation in the USA as well as other sources worldwide. Includes links to information about CAH in languages other than English.


Explain was developed as part of a project to improve communication between young people, their parents/carers and healthcare professionals in endocrine clinics. Explain was designed to help young people affected by various endocrine conditions talk with doctors and nurses, while also providing them with accessible information about those conditions.

Gene therapy for CAH – ADVANCE-CAH

Adrenas’ goal is to provide a safe and effective gene therapy treatment for adults and children living with classic CAH through the ADvance-CAH gene therapy program. 

Lab Tests Online UK – CAH information

Lab Tests Online UK has been designed to help patients better understand the many clinical laboratory tests that are part of routine care as well as diagnosis and treatment of a broad range of conditions and diseases. The site is the product of a collaboration of professional societies representing the laboratory community.

National Institute for Clinical Excellent (NICE) Treatment Summary for Adrenal Insufficiency

Including a description of Adrenal Insufficiency, treatment aims, management of the condition and other information about related medication.

The Society for Endocrinology

The Society for Endocrinology is the UK home of endocrinology. They bring together the global endocrine community to share ideas and advance the discipline of endocrinology.

You and Your Hormones

A web-based project by the Society for Endocrinology that aims to give patients and the general public access to reliable online information on endocrine science.

The CAH Support Group is affiliated with Society for Endocrinology, an organisation that supports clinicians, scientists and nurses who work with hormones throughout their careers. They engage policy-makers, journalists, patients and the public with hormone science to encourage informed health decisions, and to demonstrate the value of endocrinology to the wider world and also maintains a public information website, You and Your Hormones.

All content on this website (livingwithcah.com) is copyright the CAH Support Group unless otherwise stated.

The CAH Support Group cannot be held responsible for the content provided by any external links unless stated.

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