Educational draft · awaiting clinical reviewThe full textbook explains uncertainty but does not replace live national or local guidance, specialist advice, or current prescribing information.
Congenital adrenal hyperplasia and adrenal crisis
Paediatrics and child health · UK scope · Sources checked 27 Aug 2026 · Clinical review pending
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Suspected adrenal crisis
Vomiting, dehydration, hypotension or shock, hypoglycaemia, hyponatraemia or hyperkalaemia in a child with known or possible adrenal insufficiency is immediately life threatening.
Action: Give hydrocortisone IM or IV now: 25 mg under 1 year, 50 mg age 1 to 5 years and 100 mg from age 6 years, unless the personal plan specifies an equivalent dose. Use ABCDE, check glucose and electrolytes, give 0.9% sodium chloride 10 ml/kg boluses for shock with reassessment and treat hypoglycaemia; do not wait for cortisol results.
Overview
Recognise salt-wasting congenital adrenal hyperplasia and any childhood adrenal crisis before circulatory collapse, give hydrocortisone and isotonic fluid immediately, then provide precise glucocorticoid, mineralocorticoid, sick-day, growth, puberty and family-genetic follow-up.
Congenital adrenal hyperplasia describes inherited enzyme defects in cortisol synthesis. More than 90% are due to 21-hydroxylase deficiency. Reduced cortisol raises ACTH, producing adrenal hyperplasia and excessive androgen precursors. In classic salt-wasting disease, aldosterone synthesis is also inadequate. Non-classic disease retains more enzyme activity and presents later with androgen effects rather than neonatal salt loss. Inheritance is autosomal recessive, so diagnosis has implications for siblings and future pregnancies.
Androgen exposure can virilise external genital development in an affected 46,XX fetus, but internal Müllerian structures are present. An affected 46,XY newborn may look externally typical and later collapse from salt wasting, so appearance cannot exclude disease. Use respectful neutral language, avoid rushed sex assignment or repeated examination and involve a specialist DSD team. The UK National Screening Committee has not introduced routine national CAH blood-spot screening, making symptom recognition essential.
Practice
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Paediatrics and child healthOriginal SBA
Immediate adrenal-crisis medicine
A 3-year-old with known salt-wasting CAH is vomiting, drowsy and hypotensive, and intravenous access has not yet been obtained. What should be given immediately?
Sources and review status4 sources · checked 27 Aug 2026 · clinical review pending+
Sources
Sources and review status
National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.
NICE NG243 adrenal insufficiencyRecognition, emergency hydrocortisone, fluid resuscitation, sick-day management and crisis prevention in children.
Salt wasting often emerges after the first week as feeding demand rises and mineralocorticoid deficiency progresses. Watch for poor feeding, vomiting, weight loss beyond expectation, reduced urine, lethargy, dehydration and shock. Hyponatraemia, hyperkalaemia, acidosis and hypoglycaemia can resemble sepsis, pyloric stenosis or gastrointestinal illness. Treat sepsis when clinically possible while simultaneously considering adrenal crisis; these diagnoses can coexist.
Adrenal crisis also occurs in known CAH or other primary and central adrenal insufficiency when glucocorticoid is omitted, vomited or insufficient for fever, surgery, trauma or severe physiological stress. Use ABCDE and give hydrocortisone without waiting for confirmation. NICE age-based emergency doses are 25 mg under 1 year, 50 mg at 1 to 5 years and 100 mg from 6 years by IM or IV route. A child's personalised plan may specify an equivalent dose and should travel with them.
Restore circulation with 0.9% sodium chloride in 10 ml/kg boluses when shocked, reassessing heart rate, pulses, refill, blood pressure, consciousness and urine after each. Check bedside glucose and treat hypoglycaemia with 10% glucose under the current paediatric emergency protocol, then use glucose-containing maintenance fluid when needed. Obtain electrolytes, renal function, blood gas and infection studies. Hyperkalaemia usually improves with fluid and hydrocortisone but ECG change or severe persistent elevation needs specific emergency treatment.
If diagnosis is not known, collect cortisol, ACTH, 17-hydroxyprogesterone, renin, aldosterone, glucose, steroid profile and stored plasma or urine before hydrocortisone only when access is ready and no delay results. In a newborn with atypical genitalia, add rapid chromosomal and pelvic assessment through the specialist pathway, but immediate management follows physiology rather than presumed sex. A markedly raised 17-hydroxyprogesterone supports 21-hydroxylase deficiency; prematurity and stress can raise results and need expert interpretation.
Maintenance treatment replaces cortisol while limiting excessive adrenal androgen. Immediate-release hydrocortisone is usually divided three times daily at a total dose around 10 to 15 mg/m²/day, individualised by the endocrine team. Fludrocortisone replaces mineralocorticoid in classic salt-wasting disease, and infants may require sodium chloride supplementation because milk sodium is low and renal losses are high. Avoid chronic glucocorticoid overexposure, which suppresses height velocity and causes obesity, hypertension and Cushingoid harm.
Sick-day education prevents death. Significant fever or systemic illness usually requires oral hydrocortisone about 30 mg/m²/day in four divided doses under the BSPED plan while the child can retain medicines. Repeated vomiting, severe diarrhoea, altered consciousness, major injury or inability to swallow means give the emergency injection and seek urgent care. Minor emotional stress or a simple afebrile cold does not automatically require escalation; families need concrete examples and a written personal plan.
Long-term review balances growth, puberty and biochemical control. Undertreatment permits rapid growth initially, advanced bone age, early androgen signs and reduced adult height; overtreatment slows growth and increases cardiometabolic risk. Monitor height velocity, weight, blood pressure, pubertal stage, 17-hydroxyprogesterone and androstenedione trends, electrolytes and renin. Do not chase complete suppression of every adrenal marker with high steroid doses. Review adherence and dose timing before escalation.
Adolescents need confidential discussion about periods, fertility, genital concerns, sexuality, body image, medicine omission and emergency independence. Testicular adrenal rest tumours can occur in boys and threaten fertility, requiring specialist surveillance according to age and risk. Offer genetic counselling and explain recurrence risk. Transition must transfer emergency prescriptions, injection competence, steroid card, current dose, sick-day rules and named adult endocrine ownership.
Key points
Most congenital adrenal hyperplasia is 21-hydroxylase deficiency, causing cortisol deficiency with androgen excess; severe classic disease also causes aldosterone deficiency and salt wasting.
A newborn with atypical genital development needs urgent paediatric endocrine and differences-of-sex-development care, but a boy with salt-wasting CAH may have no external genital clue.
The UK newborn blood-spot programme does not currently screen nationally for CAH, so vomiting, weight loss and collapse in weeks two to three still depend on clinical recognition.
Adrenal crisis causes vomiting, abdominal pain, weakness, dehydration, hypotension or shock, hypoglycaemia, hyponatraemia and hyperkalaemia; fever or infection commonly triggers it.
First-line emergency medicine is hydrocortisone IM or IV immediately: 25 mg under 1 year, 50 mg from 1 to 5 years and 100 mg from 6 years, or the child's current personalised emergency dose.
Use ABCDE, check glucose and electrolytes and give 0.9% sodium chloride 10 ml/kg boluses for shock with repeated reassessment; add 10% glucose promptly for hypoglycaemia.
Take cortisol, ACTH, 17-hydroxyprogesterone, renin, aldosterone and stored samples before steroid only when this creates no treatment delay; hydrocortisone is lifesaving and takes priority.
Aetiology
01
21-hydroxylase deficiency
Biallelic CYP21A2 variants reduce cortisol and often aldosterone synthesis while diverting precursors into excess adrenal androgen production.
02
Other steroid-enzyme defects
Deficiencies including 11-beta-hydroxylase or 17-alpha-hydroxylase create different androgen, blood-pressure and electrolyte phenotypes requiring specialist steroid profiling.
03
Stress-related crisis trigger
Infection, gastroenteritis, surgery, trauma or missed replacement raises cortisol requirement beyond available endogenous or prescribed glucocorticoid.
04
Iatrogenic adrenal suppression
Prolonged systemic or potent topical, inhaled or intra-articular glucocorticoid exposure can suppress the axis and create crisis during withdrawal or illness.
Pathophysiology
1
Loss of cortisol feedback
Low cortisol removes pituitary feedback, increasing ACTH, adrenal hyperplasia and progressive accumulation of upstream steroid precursors.
2
Androgen pathway diversion
Blocked glucocorticoid synthesis channels steroid substrate toward adrenal androgens, affecting genital development, growth, bone age and puberty.
3
Mineralocorticoid salt loss
Inadequate aldosterone causes renal sodium and water loss with potassium retention, dehydration, acidosis and circulatory collapse.
4
Stress energy failure
Cortisol deficiency impairs vascular responsiveness and glucose production, so illness produces hypotension, hypoglycaemia and poor recovery from shock.
Clinical features and red flags
Salt-wasting infant
Poor feeding, vomiting, weight loss, dehydration, hyponatraemia, hyperkalaemia and hypoglycaemia develop during early weeks.
Androgen-exposed newborn
Atypical external genital development in a 46,XX infant may be the presenting sign before salt loss appears.
Known-CAH decompensation
Fever, vomiting or missed steroid is followed by weakness, abdominal pain, low glucose, hypotension and reduced responsiveness.
Non-classic androgen excess
Premature pubarche, acne, hirsutism, menstrual disturbance or advanced bone age appears without neonatal salt-wasting crisis.
Chronic undertreatment
Rapid childhood growth, early virilisation and advancing bone age accompany persistently excessive adrenal androgen production.
Adrenal crisisRed flag
Shock, severe weakness, vomiting, hypoglycaemia or major electrolyte disturbance requires hydrocortisone before diagnostic certainty.
Red flags requiring action
Shock or hypoglycaemia in possible adrenal insufficiency requires immediate hydrocortisone before confirmatory results.
Vomiting in a steroid-dependent child means oral stress dosing may not be absorbed and emergency injection is needed.
A 2-week-old boy with vomiting, weight loss, hyponatraemia and hyperkalaemia may have CAH despite typical external genitalia.
Investigations
01First-line glucose and electrolytesFirst stepFirst line
Why
Detect hypoglycaemia, sodium loss, hyperkalaemia, renal impairment and acidosis during suspected crisis.
Interpretation and limitations
The typical salt-wasting pattern supports primary adrenal disease but absence does not exclude early or central insufficiency.
02Pre-treatment cortisol and ACTH
Why
Preserve diagnostic evidence before hydrocortisone when blood can be drawn without any treatment delay.
Interpretation and limitations
Low cortisol with high ACTH supports primary failure; central disease can have low or inappropriately normal ACTH.
0317-hydroxyprogesterone
Why
Identify precursor accumulation characteristic of 21-hydroxylase deficiency in an appropriate clinical context.
Interpretation and limitations
Marked elevation supports CAH, while prematurity and stress cause lesser rises requiring age- and gestation-aware specialist interpretation.
04Renin and aldosterone
Why
Assess mineralocorticoid deficiency and guide fludrocortisone and sodium replacement after stabilisation.
Interpretation and limitations
High renin indicates inadequate effective mineralocorticoid or sodium balance; interpret with posture, salt intake and medicines.
Differential diagnosis
01
Sepsis
Infection causes lethargy, shock, glucose disturbance and acidosis and can also precipitate adrenal crisis, so parallel treatment may be necessary.
02
Pyloric stenosis
Progressive non-bilious vomiting and dehydration usually cause hypochloraemic metabolic alkalosis rather than hyperkalaemic salt-wasting acidosis in infancy.
03
Renal salt-wasting disease
Tubular disorders and pseudohypoaldosteronism cause sodium loss and hyperkalaemia but have different renin, aldosterone and steroid profiles.
04
Other DSD conditions
Androgen synthesis, action, gonadal development and maternal exposure disorders can alter genital appearance without classic 21-hydroxylase biochemistry.
05
Primary gastrointestinal illness
Vomiting and diarrhoea can explain dehydration but should not close assessment when glucose, sodium, potassium or shock are disproportionate.
Management
01Crisis resuscitationGive steroid before certaintyFirst stepA child has shock, vomiting, hypoglycaemia or major electrolyte abnormality with known or possible adrenal insufficiency.+
1Give age-banded IM or IV hydrocortisone immediately and collect diagnostic blood first only if access is already available.
2Treat shock with 0.9% sodium chloride 10 ml/kg boluses and hypoglycaemia with 10% glucose under paediatric resuscitation guidance.
3Monitor cardiac rhythm, glucose, sodium and potassium, treat sepsis or other precipitant and continue stress hydrocortisone with specialist input.
02New CAH diagnosisDefine enzyme and replacement needsSalt-wasting biochemistry, androgen effects or raised 17-hydroxyprogesterone suggests congenital adrenal hyperplasia.+
1Confirm steroid profile, ACTH, renin, aldosterone and genetics after stabilisation and involve a DSD team for atypical genital development.
Complications
01
Fatal adrenal crisis
Untreated glucocorticoid and mineralocorticoid deficiency can progress rapidly to refractory shock, arrhythmia, seizure, coma and death.
02
Hypoglycaemic brain injury
Inadequate cortisol-mediated glucose production can cause prolonged seizure and permanent neurodevelopmental harm, particularly in vulnerable infants.
03
Reduced adult height
Excess androgen advances skeletal maturation while excessive glucocorticoid suppresses growth, so either poor control can reduce final height.
04
Fertility and gonadal effects
Androgen imbalance, genital anatomy and testicular adrenal rest tissue can impair sexual function, spermatogenesis or fertility.
05
Treatment cardiometabolic harm
Chronic glucocorticoid or mineralocorticoid excess contributes to obesity, hypertension, insulin resistance and reduced long-term bone health.
Monitoring and follow-up
Plot height, weight and BMI and calculate height velocity, looking for both androgen-driven acceleration and glucocorticoid suppression.
Measure blood pressure, sodium, potassium and renin to assess mineralocorticoid and salt replacement.
Follow 17-hydroxyprogesterone and androstenedione trends at consistent dose timing rather than reacting to one isolated result.
Assess pubertal stage, menstrual health, bone age when growth changes and testicular findings according to specialist surveillance.
At every visit inspect emergency-kit expiry, steroid card, school plan and whether family members can demonstrate injection preparation.
Review crisis episodes, vomiting decisions, missed doses, supply access, mental health and safeguarding without blame.
Update weight or body-surface-area prescriptions and transfer a precise sick-day and perioperative plan to adult care.
Special situations
Boys can look unaffected
A salt-wasting 46,XY infant may have typical external genitalia and present only when electrolyte loss becomes critical.
Screening does not rescue recognition
CAH is not part of the current national UK blood-spot panel, so symptoms and biochemistry remain decisive.
Hydrocortisone is the diagnostic priority
A pretreatment sample is useful only when immediately obtainable; lifesaving steroid must never wait for laboratory completeness.
Vomiting defeats oral stress doses
Emergency injection is needed when replacement cannot be retained, even if an oral dose was attempted minutes earlier.
Perfect suppression can be harmful
Chasing very low adrenal markers with high glucocorticoid can sacrifice growth and create obesity and hypertension.
Common pitfalls
01
Assuming typical male genital appearance excludes classic CAH.
02
Waiting for a cortisol result before giving emergency hydrocortisone.
03
Treating vomiting with repeated oral steroid that is not absorbed.
04
Forgetting simultaneous sepsis treatment when infection may have triggered crisis.
05
Rushing sex assignment or repeating genital examinations without a specialist, consent and sensitivity.
06
Using dexamethasone chronically for routine childhood CAH growth control.
07
Driving every 17-hydroxyprogesterone result into the normal range with excessive hydrocortisone.
08
Providing only one injection kit without school, travel and expiry planning.
During significant illness, use the written BSPED sick-day plan, commonly hydrocortisone 30 mg/m²/day in four divided oral doses when absorption is reliable, and inject if vomiting prevents dosing.
Classic CAH maintenance usually combines oral hydrocortisone in three divided doses with fludrocortisone, and infants may need sodium supplementation; a paediatric endocrinologist adjusts from growth, blood pressure, electrolytes, renin and androgen control.
Every child needs two emergency injection kits, a steroid emergency card, trained carers and school, travel supplies, medical identification and a plan for fasting, surgery, injury and transition.
Atypical genital development requires urgent electrolyte and glucose assessment as well as respectful DSD referral.
Severe hyperkalaemia with ECG change requires specific resuscitation alongside steroid and fluid replacement.
Headache, visual symptoms or multiple pituitary deficits suggests central adrenal insufficiency from intracranial disease.
Repeated crises may indicate inadequate supplies, misunderstanding, access barriers, deliberate omission or safeguarding concerns.
05Steroid profile and genetics
Why
Confirm enzyme mechanism, distinguish rarer CAH forms and provide accurate family recurrence counselling.
Interpretation and limitations
Results should be integrated by a specialist because pathway intermediates and genotype-phenotype relationships can overlap.
06DSD and anatomical assessment
Why
Use rapid chromosomes and targeted pelvic imaging with specialist examination when genital development is atypical.
Interpretation and limitations
Gonadal and internal anatomy inform diagnosis, but no single appearance or scan should force rushed sex assignment.
2
Begin hydrocortisone and, for salt-wasting disease, fludrocortisone and infant sodium supplementation using endocrine prescriptions.
3Teach inheritance, emergency injection, sick days and weight-based plan changes before discharge and arrange family testing or counselling.
03Intercurrent illnessMatch cortisol to physiological stressA steroid-dependent child develops significant fever, infection, surgery, trauma, diarrhoea or vomiting.+
1Use the written plan, commonly oral hydrocortisone 30 mg/m²/day in four divided doses for significant illness when doses stay down.
2Inject hydrocortisone and seek urgent care for vomiting, severe illness, altered consciousness, major injury or inability to swallow.
3Maintain carbohydrate and fluid, monitor glucose when vulnerable and return to maintenance only after recovery according to the plan.
04Long-term balanceControl androgen without suppressing growthThe child attends routine CAH review or shows altered growth, puberty, blood pressure or biochemical control.+
1Review actual dose timing, adherence, growth velocity, weight, blood pressure, bone age and pubertal development.
2Adjust hydrocortisone, fludrocortisone and salt using clinical pattern, electrolytes, renin and androgen trends without normalising every marker aggressively.
3Address fertility, testicular adrenal rest risk, body image, mental health and emergency independence through adolescence and transition.
Key medicines and prescribing safety3 treatments · regimens, roles and cautions+
Replaces absent stress cortisol, restores vascular responsiveness and supports glucose during adrenal crisis.
Emergency hydrocortisone
Give intramuscularly or intravenously immediately: 25 mg under age 1 year, 50 mg from age 1 to 5 years and 100 mg from age 6 years, unless the child's current emergency plan provides an equivalent personalised dose.
Do not delay for blood sampling or IV access because IM administration is effective; continue stress replacement and taper only with endocrine guidance after recovery.
Classic CAH maintenance is commonly 10 to 15 mg/m²/day orally in three divided doses; for significant illness with reliable absorption, BSPED plans commonly use 30 mg/m²/day in four divided doses.
Vomiting requires injection, not repeated oral dosing; chronic excess impairs growth and causes metabolic harm, while underdosing risks androgen excess and crisis.
Replaces mineralocorticoid activity to retain sodium, excrete potassium and maintain circulating volume.
Fludrocortisone
Give the endocrine-prescribed oral dose, often 50 to 200 micrograms daily in one or two doses for classic salt-wasting CAH, titrated to blood pressure, electrolytes and renin; infants may also need sodium chloride.
Excess causes hypertension, suppressed renin, oedema or hypokalaemia; requirements and sodium supplementation change rapidly during infancy and growth.