Congenital Adrenal Hyperplasia (CAH)

Classic and non-classic CAH

More than nine out of ten cases are caused by a deficiency of the enzyme 21-hydroxylase, inherited in an autosomal recessive pattern. How much enzyme activity remains determines which form a person has.

• Classic, salt-wasting — The most severe form. Usually identified on newborn screening because of adrenal crisis risk in the first weeks of life.
• Classic, simple virilizing — Cortisol is low and androgens are high, but salt balance is preserved.
• Non-classic (late-onset) — Much more common and often missed. Frequently first diagnosed in adolescence or adulthood.

Signs that bring adults to us

Non-classic CAH is regularly mistaken for PCOS. If you've been treated for irregular cycles or unwanted hair growth without a clear answer, it's worth a proper adrenal work-up.

• Irregular or absent periods
• Excess hair growth (hirsutism) and persistent acne
• Scalp hair thinning
• Difficulty conceiving
• Early puberty or rapid early growth with a shorter final adult height
• Fatigue, low blood pressure, or salt craving

How we diagnose CAH

Timing matters for these labs — 17-hydroxyprogesterone should be drawn early in the morning, and in menstruating patients during the follicular phase. We handle the sequencing so results are interpretable the first time.

• Morning 17-hydroxyprogesterone — The primary screening test for 21-hydroxylase deficiency.
• ACTH (cosyntropin) stimulation test — Confirms the diagnosis when baseline values are borderline.
• Full adrenal and androgen panel — Cortisol, ACTH, renin, electrolytes, testosterone, DHEAS and androstenedione.
• CYP21A2 genetic testing — Confirms the diagnosis and informs family planning and carrier counseling.

Treatment and long-term management

The goal is to replace what the adrenal glands cannot make while using the lowest effective dose — enough to control androgen excess, not so much that patients carry the weight, bone and metabolic costs of over-replacement. That balance is the whole art of managing CAH, and it changes with age, pregnancy and illness.

• Glucocorticoid replacement — Hydrocortisone, prednisone or dexamethasone, dosed and timed to the individual.
• Mineralocorticoid replacement — Fludrocortisone, with salt supplementation, for salt-wasting CAH.
• Crinecerfont (Crenessity) — A newer non-steroidal option that lowers ACTH drive and can allow glucocorticoid doses to be reduced in eligible patients.
• Sick-day and stress dosing — A written plan, an emergency injectable hydrocortisone kit, and medical alert identification.
• Fertility and pregnancy care — Cycle regulation, ovulation support, and co-management through pregnancy.
• Ongoing monitoring — Growth and bone density, blood pressure, metabolic labs and adrenal hormone levels.

Transitioning from pediatric to adult care

Many people with classic CAH are diagnosed as infants and followed by a pediatric endocrinologist for two decades. The handoff to adult care is where patients most often fall out of follow-up — and where adrenal crises happen. We take that transition seriously and build a plan you can actually keep up with as an adult.