Congenital Adrenal Hyperplasia Cah

Overview

Congenital adrenal hyperplasia (CAH) is a condition a person is born with that affects the adrenal glands. These are two small glands that sit on top of the kidneys and make hormones — chemical messengers the body uses to control things like stress response, salt balance, growth, and puberty. In CAH, a tiny change in a gene means one of the steps in making these hormones does not work properly. The body ends up short of two important hormones (cortisol, the 'stress hormone', and sometimes aldosterone, which keeps salt and water in balance) and makes too much of male-type hormones (androgens). CAH is not caused by anything a parent did or did not do, and it is not contagious.

CAH is uncommon. The classic form affects roughly 1 in every 15,000 to 20,000 babies in many populations. The non-classic form is more common and is thought to affect around 1 in 100 to 1 in 1,000 people, depending on the population. Because it is uncommon, many people — including some health professionals — may not have seen it before, so specialist care matters.

CAH affects boys and girls equally, and people of all ethnic backgrounds. It is present from birth, even if it is not noticed until later. The non-classic form is more often picked up in later childhood or adulthood, and it is more common in some ancestry groups, such as people of Ashkenazi Jewish, Hispanic, Italian, or Yugoslav heritage.

Symptoms

Common symptoms

• In classic CAH, signs often appear in the first days or weeks of life: poor feeding, vomiting, sleepiness, weight loss, and dehydration.
• In baby girls, the genitals may look different from usual at birth (for example, an enlarged clitoris or genitals that are not clearly male or female).
• In non-classic CAH, signs may include early puberty, acne, extra body or facial hair, irregular periods, and problems getting pregnant.
• Some people have no obvious signs at all until they are unwell or until tests are done for another reason.

Symptoms in children

• Early growth of pubic or underarm hair, body odour, or acne before the usual age.
• Growing fast in height at first, then finishing growth early and ending up shorter than expected as an adult.
• An enlarged clitoris or genitals that look unusual.
• In classic CAH, poor weight gain, vomiting, and dehydration in the first weeks of life.
• Behaviour changes such as irritability or unusual sleepiness when unwell.

Symptoms in older adults

• Non-classic CAH may first be noticed in adulthood as acne, excess facial or body hair, or thinning scalp hair.
• Irregular or absent periods, or difficulty becoming pregnant.
• Tiredness or low energy that is hard to explain.
• Reduced fertility in men, sometimes with small testicular lumps found on examination.
• Adults with classic CAH may notice long-term effects such as shorter final height, weight changes, or reduced bone strength.

Causes

Main causes

• CAH is caused by a change (variant) in a gene, usually the gene called CYP21A2, that carries the instructions for one of the enzymes the adrenal glands use to make hormones.
• Because one step in the hormone-making pathway is blocked, the body cannot make enough cortisol, and in many cases not enough aldosterone either.
• The same block causes the body to make extra male-type hormones (androgens), which is why puberty changes and genital development can be affected.
• It is inherited in a 'recessive' pattern: a child develops CAH only if they inherit the changed gene from both parents. Parents are usually healthy carriers with no symptoms.

Risk factors

• A family history of CAH, or parents who are known carriers of a CYP21A2 gene variant.
• Parents who are related by blood (consanguinity) have a higher chance of both carrying the same rare gene variant.
• Certain ancestry backgrounds are linked with a higher chance of the non-classic form.
• Having one affected child means any future child has a higher chance of CAH — genetic counselling can explain the exact odds.

When to see a doctor

See a doctor urgently if:

• A newborn who is not feeding well, is vomiting repeatedly, is unusually sleepy, or is losing weight.
• A baby or child with genitals that look unusual — this should be looked at promptly by a specialist team.
• Anyone with CAH who becomes ill with vomiting, diarrhoea, or fever and cannot keep their medicine down.
• Signs of dehydration, collapse, or severe weakness at any age — call your local emergency number.
• A child showing signs of puberty very early (pubic hair, body odour, acne, or breast or genital changes before about age 8 in girls or 9 in boys).

Book a routine appointment if:

• You have a family history of CAH and are planning a pregnancy or already pregnant — ask about genetic counselling.
• You have irregular periods, troublesome acne, or extra hair growth and wonder whether hormones could be involved.
• You have been trying to conceive without success.
• You or your child have CAH and are due a routine review of growth, blood pressure, or blood tests.
• You are changing schools, jobs, or moving country and need a plan for medicines and emergency care.

Diagnosis

CAH is diagnosed with a combination of a physical examination, blood tests, and sometimes genetic testing. In the UK and many other countries, every newborn has a heel-prick blood spot test that includes a screen for classic CAH, so most classic cases are found in the first week or two of life. Non-classic CAH is usually found later, when someone has symptoms such as early puberty or irregular periods, and is confirmed with hormone tests.

Tests that may be done

• Newborn blood spot (heel-prick) screening — a few drops of blood from the baby's heel are tested for hormone levels.
• Blood tests to measure adrenal hormones and the hormone that controls them (ACTH), plus salt levels (sodium and potassium).
• A 'stimulation test' — a hormone is given and blood is sampled afterwards to see how the adrenal glands respond. This helps tell classic from non-classic CAH.
• Genetic testing (a blood or saliva sample) to look for the gene variant and to help with family planning.
• Blood pressure checks, growth and height measurements, and bone age X-rays in children.
• Ultrasound scans, and sometimes scans of the testes in men, to check for related changes.

What to expect at your appointment

You may be seen by a paediatrician or an adult endocrinologist (a hormone specialist), often within a team that includes a specialist nurse, a genetic counsellor, and a psychologist. Some results come back within days; genetic results can take several weeks. You will usually be given clear written information and a plan for what to do if your child — or you — becomes unwell. It is fine to bring someone with you and to write down your questions in advance.

Treatment

CAH cannot be cured, but it can be managed very well. Treatment replaces the hormones the adrenal glands cannot make, and aims to keep growth, puberty, blood pressure, salt balance, and general health on track. Treatment is lifelong and is tailored to each person, with regular check-ups to fine-tune it.

Self-care at home

• Take your hormone medicine exactly as prescribed, at the same times each day — never stop suddenly on your own.
• Learn your 'sick day rules': most people with CAH need extra medicine during illness, fever, injury, or surgery. Your team should give you a written plan.
• Wear or carry medical ID stating that you have CAH and take steroid (hormone) medicine.
• Keep an emergency supply of medicine and, where your team advises, an injectable emergency dose, and teach family members how to use it.
• Tell teachers, coaches, and employers about CAH and what to do in an emergency.
• Carry a card or letter from your team explaining your condition for emergency staff.
• Attend all routine appointments, even when you feel well.
• Keep up to date with routine vaccinations, and ask your team about extra ones such as flu and pneumonia vaccines.

Medical treatments

Treatment uses medicines that replace the hormones the body is missing — a form of cortisol taken every day (often two or three times a day), and for many people a second medicine that helps the body hold on to salt. Babies and children are checked regularly for growth, blood pressure, and blood tests, and doses are adjusted as they grow. During illness, injury, or surgery, the dose is temporarily increased — this is often called 'stress dosing' or 'sick day rules'. Women with irregular periods or fertility concerns may be offered additional hormone treatment, and some people are offered medicines to slow early puberty. Every person's plan is different, so your specialist team will explain exactly what is right for you. Never change or stop treatment without speaking to them.

When is surgery considered?

Some baby girls and children with genitals that look different may be offered surgery. This is a sensitive and personal decision, and current guidance recommends waiting until the child is old enough to be involved in the decision wherever possible, except where surgery is needed for health reasons. Families are entitled to full information, psychological support, and time to consider options. Surgery is not needed for CAH itself — only for particular physical features, and only after careful discussion with a specialist team.

Living with this condition

Day-to-day life with CAH is mostly about routine: taking medicine on time, keeping spare supplies, and knowing what to do when illness strikes. Many people with CAH work, study, play sport, travel, and have families. Planning ahead — for exams, travel, surgery, or a stomach bug — makes a big difference. Your specialist team can help you build a simple personal plan.

Lifestyle tips

• Keep a written emergency plan at home, at school, and at work.
• Carry medical ID and emergency medicine when travelling; check airline rules for carrying medicines and keep them in hand luggage.
• Get enough sleep and manage stress — the body handles illness and stress better when you are rested.
• Avoid extreme crash diets or unsupervised supplement use, which can affect hormones and salt balance.
• Ask your team before starting new medicines, including herbal remedies, as some interact with hormone treatment.
• Build a good relationship with a pharmacist who can advise on interactions and supply issues.

Diet and exercise

There is no special diet for CAH, but balanced eating and staying active support general health, bone strength, and a healthy weight. Some people with CAH are advised to keep an eye on salt — but do not cut salt out unless your team tells you to, because the body needs salt to keep blood pressure and fluid balance right. Regular weight-bearing exercise such as walking, dancing, or climbing stairs helps keep bones strong. If you take hormone medicine, try to take it with food at consistent times. Ask your team or a dietitian for advice tailored to you.

Mental health and emotional wellbeing

Living with a long-term condition can affect how you feel. Some people with CAH — and parents of children with CAH — experience worry, low mood, or difficulty with body image, especially around puberty or if genital appearance has been a concern. These feelings are common and treatable, and they are not a sign of weakness. Talk to your GP or specialist team; psychological support is often available as part of CAH care. If you or someone you care for is having thoughts of self-harm or suicide, contact your local emergency number or a crisis line in your country straight away — do not wait.

Prevention

CAH cannot be prevented — it is written into a person's genes from conception, and nothing a parent does or does not do causes it. What can be done is to plan ahead: genetic counselling can explain the chance of passing CAH on, and prenatal testing is available for families at higher risk. Early diagnosis and steady treatment prevent the most serious complications.

Vaccines

There is no vaccine for CAH. However, routine childhood vaccinations and recommended adult vaccines (such as flu and pneumonia vaccines) matter more for people with CAH, because infections can trigger an adrenal crisis. Ask your GP or specialist team which vaccines are advised for you.

Screening programmes

Newborn blood spot screening detects classic CAH in many countries, including the UK, and allows treatment to start before a crisis happens. There is no routine screening programme for non-classic CAH; it is found through testing when symptoms suggest it. If you have a family history, ask about genetic counselling and, if you are pregnant, about prenatal testing options.

Complications

If left untreated

• Adrenal crisis — a life-threatening drop in cortisol, with vomiting, dehydration, low blood pressure, and collapse. This is a medical emergency.
• Severe salt loss and dehydration in babies with the salt-wasting form of CAH.
• Rapid growth in childhood followed by early stopping of growth, leading to shorter adult height.
• Early puberty, and in some people, reduced fertility.
• Irregular periods, acne, and excess hair growth in non-classic CAH.
• Benign testicular lumps (adrenal rest tissue) in some men, which can affect fertility if not monitored.
• Reduced bone strength or changes in weight and blood pressure if treatment is not well balanced.
• Ongoing worry, low mood, or body-image concerns, especially if psychological support is not offered.

Long-term outlook

The outlook today is good. Because newborn screening and hormone treatment work well, most children with CAH grow up healthy, go to school, work, and have relationships and families of their own. Regular check-ups help keep treatment balanced, catch problems early, and adjust doses as bodies change. Some people face extra challenges — with growth, fertility, or body image — and these deserve honest conversation and support. If you have CAH, or care for someone who does, you are entitled to a specialist team, clear information, and a plan you feel confident in.

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