What's congenital adrenal hyperplasia?
Classic congenital adrenal hyperplasia is an inherited disorder of the adrenal glands. A missing enzyme, 21-hydroxylase, blocks the glands from making enough cortisol (and often aldosterone), so the body instead overproduces male-type hormones (androgens). The result is a combination of hormone deficiency and androgen excess. This severe 'classic' form usually appears in newborns and is distinct from the milder, later-onset 'non-classic' form.
| Also indexed as | OMIM:201910, MONDO:0008728 |
|---|---|
| Features mapped | 15 |
| Treatments mapped | 2 |
| Published sources | 17 |
| Last reviewed | 2026-08-04 |
Signs and symptoms
Renal salt wasting
In the classic salt-wasting form of congenital adrenal hyperplasia, the body cannot hold on to salt, which can trigger a dangerous salt-wasting crisis. If the condition is not recognized, these crises can be life-threatening in newborns.
Hypoglycemia
Because congenital adrenal hyperplasia reduces cortisol, blood sugar can drop too low (hypoglycemia), especially in babies and during illness or a salt-wasting crisis. Low blood sugar can cause sluggishness, jitteriness, or seizures and needs prompt treatment.
Hypertension
People with congenital adrenal hyperplasia can develop high blood pressure, both from the disease itself and sometimes from the steroid medicines used to treat it. Blood pressure is monitored as part of long-term care.
Autosomal recessive inheritance
Congenital adrenal hyperplasia is inherited in an autosomal recessive way, meaning a child is affected only when a changed gene is inherited from each parent; most cases come from changes in the CYP21A2 gene.
Primary adrenal insufficiency
The adrenal glands cannot make enough cortisol, and in the salt-wasting form not enough aldosterone either. This adrenal insufficiency is why daily hormone replacement is needed and why illness or stress requires extra steroid to avoid a dangerous adrenal crisis.
Increased circulating ACTH level
When cortisol is low in 21-hydroxylase deficiency, the brain loses its normal off-switch on the adrenal glands, so levels of ACTH (the hormone that drives the adrenals) and adrenal androgens rise. This drive is what keeps the adrenal glands overactive.
Precocious puberty in females
Because congenital adrenal hyperplasia floods the body with extra androgens, children can enter puberty early, with signs such as early pubic hair and a growth spurt. In girls this early (precocious) puberty is a common reason the condition is recognized in childhood.
Premature pubarche
In the simple virilizing form of classic 21-hydroxylase deficiency, children can grow faster than expected, show advanced bone age, and develop pubic hair early.
Decreased circulating cortisol level
In classic congenital adrenal hyperplasia from 21-hydroxylase deficiency, the adrenal glands cannot make enough cortisol, the body's main stress hormone. In the most severe salt-wasting form this cortisol shortage shows up in the newborn period alongside a shortage of aldosterone.
Elevated circulating 17-hydroxyprogesterone concentration
A raised level of 17-hydroxyprogesterone (17-OHP) in the blood is the key diagnostic marker, because the blocked enzyme makes this precursor pile up. It is the basis of newborn screening for the condition and is used to monitor treatment.
Increased circulating androgen concentration
Because the blocked pathway diverts building blocks into male-type hormones, androgen levels are high. In girls this can cause virilization; in both sexes it can speed up early growth and bone maturation if not controlled.
Hirsutism
In the milder, non-classic form of 21-hydroxylase deficiency, adolescent girls and women may have severe acne, excess hair growth in a male pattern (hirsutism), thinning scalp hair, or irregular or absent periods.
Acne
In the milder, non-classic form of 21-hydroxylase deficiency, adolescent girls and women may have severe acne along with excess hair growth, thinning scalp hair, or irregular or absent periods.
Ambiguous genitalia, female
In congenital adrenal hyperplasia the excess androgens can change the appearance of the external genitalia in 46,XX (female) babies, with differences such as an enlarged clitoris or a single urogenital opening. The degree of change varies from child to child.
Accelerated skeletal maturation
The extra adrenal androgens in 21-hydroxylase deficiency often speed up bone growth and maturation, so the growth plates can close early. Growing fast at first can mean a shorter final adult height.
How it is diagnosed
Adrenal hyperplasia, congenital, due to 21-hydroxylase deficiency
Diagnosed using: 17-hydroxyprogesterone.
“In cases of 21-OHD, the diagnosis is based on the 17-hydroxyprogesterone (17-OHP) level being above 1000 ng/dL, measured early in the morning.”
Adrenal hyperplasia, congenital, due to 21-hydroxylase deficiency
Diagnosed using: ACTH stimulation test.
“In cases with borderline 17-OHP levels (200-1000 ng/dL), it is recommended to perform an adrenocorticotropic hormone (ACTH) stimulation test.”
Treatment and management
What the research describes, not a recommendation. Treatment decisions belong with your clinician.
This covers treatments that appear in the published research mapped here. Investigational and experimental therapies are not included, so their absence is a boundary of this map, not a sign they do not exist.
hydrocortisone
Hydrocortisone is the main glucocorticoid used to replace the cortisol the adrenal glands cannot make in congenital adrenal hyperplasia, and it remains the primary therapy.
Used to help with: Adrenal hyperplasia, congenital, due to 21-hydroxylase deficiency.
“…treated with hydrocortisone, 9α-fludrocortisone, and sodium…”
fludrocortisone
Fludrocortisone replaces the missing aldosterone in the salt-wasting form, helping the body keep salt and water and maintain blood pressure. Infants often also need extra salt. The dose is adjusted using blood pressure, salt levels, and a hormone called renin.
Used to help with: Adrenal hyperplasia, congenital, due to 21-hydroxylase deficiency.
“…hydrocortisone, 9α-fludrocortisone, and sodium…”
What changes how it shows up
Carrying the genetic change is not the whole story. The factors below are described in the research mapped here as changing whether, or how strongly, the condition appears. They modulate how the genotype is expressed; they do not, on their own, cause or cure it.
salt-wasting vs simple-virilizing vs nonclassic form
21-hydroxylase deficiency spans a range of severity that is generally grouped into three forms: the classic form, which includes the salt-wasting and simple virilizing types, and the milder nonclassic form.
Described as modulating: Adrenal hyperplasia, congenital, due to 21-hydroxylase deficiency.
“The classic form encompasses salt-wasting and simple virilizing CAH and the least affected form is termed nonclassic CAH.”
CYP21A2 genotype basis
Most congenital adrenal hyperplasia is caused by 21-hydroxylase deficiency, which results from changes (mutations) in the CYP21A2 gene.
Described as modulating: Adrenal hyperplasia, congenital, due to 21-hydroxylase deficiency.
“The most common form of CAH is 21-hydroxylase deficiency, caused by mutations in the CYP21A2 gene.”
How to read the evidence labels
Where this comes from
This guide is built from 17 published source(s). Every claim above links back to one of them. Click any source ID to read the original on PubMed.
Take it further
Printed, source-linked documents built from this condition's graph — ready to bring to an appointment or attach to a coverage request. Every claim carries its published source, the same as this guide.