17817 Congenital Adrenal Hyperplasia

Overview

Congenital adrenal hyperplasia (CAH) is an inherited condition that affects the adrenal glands, two small hormone-producing glands located on top of the kidneys. These glands make important hormones like cortisol, which helps the body handle stress and illness, and aldosterone, which helps control salt and water balance. In CAH, a missing or faulty enzyme prevents the adrenal glands from making cortisol properly, and sometimes aldosterone too. Instead, the body produces extra androgens (male sex hormones), which can cause a range of symptoms.

CAH is rare. About 1 in 14,000 to 18,000 babies are born with the classic form. A milder form, called non-classic CAH, is more common and affects about 1 in 1,000 people in some populations.

CAH affects people of all ethnic backgrounds and both sexes. The classic form is usually detected at birth through newborn screening. The milder form can appear later in childhood or young adulthood.

Symptoms

Common symptoms

• In infants: poor feeding, vomiting, dehydration, low blood sugar, and tiredness.
• In children and adults: early puberty, rapid growth but shorter final height, acne, excessive body hair, irregular menstrual periods, and fertility problems.
• In non-classic CAH: symptoms may be mild or absent, and can include acne, excess hair growth, and irregular periods in women.

Symptoms in children

• Poor weight gain, feeding difficulties, vomiting, and dehydration.
• Genitals that look different in newborn girls (enlarged clitoris or fused labia).
• Boys may have a very large penis at birth, but otherwise look typical.
• Rapid growth during childhood but early bone maturation, leading to a shorter adult height.

Symptoms in older adults

• Long-term treatment is common, but possible issues include reduced bone density, fertility problems, and fatigue.
• Signs of excess androgens, such as balding, acne, or mood changes.
• Risk of adrenal crisis if medication is missed or during illness, injury, or stress.

Causes

Main causes

• CAH is caused by a mutation (change) in a gene that provides instructions for an enzyme needed to make cortisol in the adrenal glands.
• It is inherited in an autosomal recessive pattern, meaning a child must inherit a faulty gene from both parents to have CAH.

Risk factors

• Having a family history of CAH.
• Being a child of parents who are both carriers of the CAH gene.
• Certain ethnic groups have higher rates of non-classic CAH, including Ashkenazi Jews, Hispanics, and people of Mediterranean descent.

When to see a doctor

See a doctor urgently if:

• If you or your child show signs of adrenal crisis — severe vomiting, dehydration, low blood sugar, or altered alertness.
• If your child with CAH is ill and cannot keep down oral medications.

Book a routine appointment if:

• If you have symptoms like irregular periods, excessive hair growth, or unexplained fatigue.
• If you are planning a pregnancy and have a family history of CAH or are a known carrier.

Diagnosis

Doctors diagnose CAH using a combination of physical examination, blood and urine tests, and genetic testing. Newborn screening in many countries can detect classic CAH in the first days of life.

Tests that may be done

• Blood test to measure 17-hydroxyprogesterone, cortisol, and other hormone levels.
• Salt and electrolyte tests to check for aldosterone deficiency.
• Genetic test to confirm the specific gene mutation.

What to expect at your appointment

Your doctor may refer you to an endocrinologist, a specialist in hormone disorders. The diagnostic process may involve a few appointments and tests. It helps to bring a list of your symptoms and any family history of hormone problems.

Treatment

Treatment for CAH focuses on replacing the hormones the body cannot make naturally. With regular medication and monitoring, most people live normal, full lives.

Self-care at home

• Learn the signs of adrenal crisis and always carry emergency medical identification, such as a bracelet or card.
• Never skip doses of your prescribed medication.
• During illness, injury, or stress, you may need extra medication — always follow your care plan and talk with your care team in advance.

Medical treatments

Treatment usually involves hormone replacement therapy to replace cortisol and, if needed, aldosterone. The exact medication and dose are tailored to each person and are adjusted with age, weight, and response. Children may also need medication to manage excess androgens and support normal growth and puberty. Never change or stop medication without speaking to your doctor.

When is surgery considered?

Some girls and women with ambiguous genitalia may have surgery in infancy or later to improve function and appearance. This is a personal choice, and you should discuss the risks and benefits thoroughly with your surgical and endocrinology team.

Living with this condition

Managing CAH involves taking daily medication, attending regular check-ups, and adjusting medication during stress or illness. Most people learn to manage their condition confidently with the support of their healthcare team.

Lifestyle tips

• Carry a 'sick day' plan agreed with your care team for illness.
• Wear a medical alert bracelet or keep an alert card in your wallet.
• Keep an emergency supply of medication at home and when travelling.

Diet and exercise

Eat a normal balanced diet. Exercise is safe and recommended for everyone. Let your care team know if you increase training intensity, as your medication may need adjusting.

Mental health and emotional wellbeing

Living with a chronic condition like CAH can be emotionally challenging, especially for teenagers and adults with concerns about appearance, fertility, or body image. It is normal to feel this way, and speaking with a counsellor or psychologist can help. If you are in crisis, reach out to a local mental health helpline.

Prevention

CAH is a genetic condition, so it cannot be prevented. However, genetic counselling can help families understand their risk, and early testing allows treatment to begin at birth.

Vaccines

No vaccine prevents CAH, but staying up to date with routine vaccinations is especially important for anyone with adrenal insufficiency.

Screening programmes

Many countries offer newborn screening for CAH. If you have a known family history, genetic testing during pregnancy may be available.

Complications

If left untreated

• Slow growth and shorter final height.
• Severe salt loss leading to dehydration and shock (adrenal crisis).
• Ambiguous genitalia in newborn girls.
• Infertility in some people with CAH.

Long-term outlook

With early diagnosis and lifelong treatment, most people with CAH have a normal lifespan and good quality of life. Many go on to have families. The key to a good outcome is consistent medication, regular monitoring, and a supportive care team.

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