Synopsis
Understand the enzyme defect and salt-wasting risk, maintain life-saving cortisol replacement without chronic excess, and coordinate growth, puberty, fertility, genetics and crisis prevention across specialist care.
- Congenital adrenal hyperplasia is a group of inherited steroid-synthesis disorders; 21-hydroxylase deficiency causes most cases and produces cortisol deficiency with excess adrenal androgen, plus aldosterone deficiency in salt-wasting disease.
- Classic salt-wasting CAH can present in infancy with vomiting, weight loss, dehydration, hyponatraemia, hyperkalaemia and shock; newborn screening and genital appearance do not identify every affected child.
- Treatment replaces glucocorticoid and, when deficient, mineralocorticoid while restraining excess ACTH and androgen; complete biochemical suppression at the cost of iatrogenic Cushing syndrome is not the goal.
- Adults need reliable daily medication, sick-day dosing, emergency injection training, two or more kits under NICE guidance, and an NHS Steroid Emergency Card.
- Hydrocortisone is first-choice routine adult replacement at a total 15 to 25 mg daily in divided doses, with any higher CAH dose determined by specialist biochemical and clinical goals.
- Fludrocortisone need is judged from blood pressure, postural symptoms, potassium, sodium and renin; excessive dosing causes hypertension, oedema and renin suppression.
- Male fertility can be impaired by testicular adrenal rest tumours and gonadotrophin suppression, while women may have androgen-related anovulation, genital or sexual-health concerns and complex pregnancy planning.
- Never stop replacement abruptly, and treat suspected adrenal crisis immediately with parenteral hydrocortisone and isotonic saline while the precipitating illness is managed.
Key red flags
Vomiting, diarrhoea, hypotension, confusion, hypoglycaemia or collapse in steroid-dependent CAH is adrenal crisis until assessed and needs immediate emergency hydrocortisone.
An infant with dehydration, hyperkalaemia and hyponatraemia requires urgent paediatric endocrine treatment even when external genital appearance is typically male.
Failure to retain oral glucocorticoid during illness demands injected replacement and emergency hospital assessment rather than repeated tablets at home.
Severe headache, hypertension or neurological symptoms during pregnancy require obstetric assessment; steroid changes and delivery cover belong with a specialist endocrine-obstetric team.
A new testicular mass must not be assumed to be benign adrenal rest tissue without ultrasound and specialist evaluation for competing diagnoses.
Investigation priorities
Identify the characteristic precursor elevation and follow biochemical control in 21-hydroxylase deficiency.
Management branches
A steroid-dependent person is haemodynamically unwell, hypoglycaemic or unable to absorb oral replacement.
- Give intramuscular or intravenous hydrocortisone immediately; obtaining cortisol or ACTH must never delay treatment.
- Call emergency services, establish monitoring and restore circulation with 0.9% sodium chloride while checking glucose and electrolytes.
- Continue stress-dose hydrocortisone by infusion or divided parenteral doses according to NICE and seek endocrine advice.
- Identify infection, gastroenteritis, missed treatment or another precipitant, then return to oral sick-day dosing only after absorption and stability recover.
Classic CAH is established and the patient is clinically stable on oral therapy.
- Use the lowest glucocorticoid regimen that preserves wellbeing and acceptable androgen control without Cushingoid toxicity.
- Adjust fludrocortisone from clinical volume status, blood pressure, electrolytes and renin rather than a fixed lifelong dose.
- Standardise hormone sampling to dose timing and review adherence, shift work, exercise and interacting medicines before changing treatment.
- Rehearse sick-day rules, injection technique, emergency kit expiry and card carriage at every meaningful review.