Adrenal hyperplasia in adults refers to bilateral enlargement of the adrenal glands caused by sustained ACTH drive, most often from an inherited steroidogenesis enzyme defect. The classic example is 21-hydroxylase deficiency, which impairs cortisol synthesis and diverts precursors into androgens. In adults it usually appears as nonclassic congenital adrenal hyperplasia, with androgen excess rather than salt wasting. Prevalence estimates for the nonclassic form sit around 1 in 100 to 1 in 1,000 in general populations, and up to 1–2 percent in women evaluated for hyperandrogenism. Symptoms include hirsutism, oligomenorrhea, acne, and infertility. Diagnosis rests on a 17-hydroxyprogesterone level measured in the early follicular morning.
What Adrenal Hyperplasia Means at the Gland Level
The adrenal cortex runs a five-step assembly line. Cholesterol enters, gets cleaved to pregnenolone, and then travels down one of three branches: mineralocorticoid, glucocorticoid, or androgen. Each branch depends on a specific enzyme. When one enzyme is partly disabled, the substrate behind it piles up and gets pushed down whichever branch still works. The pituitary senses low cortisol and raises ACTH, which inflates the whole cortex. Hyperplasia, in other words, is a downstream symptom of a blocked assembly line, not a tumor process.
In 21-hydroxylase deficiency the blocked step is cortisol and aldosterone synthesis. The backlog of 17-hydroxyprogesterone shunts into the androgen pathway. That single enzyme accounts for roughly 95 percent of all congenital adrenal hyperplasia cases. Less common defects include 11-beta-hydroxylase deficiency, which pushes precursors into both androgens and deoxycorticosterone, and 3-beta-hydroxysteroid dehydrogenase deficiency. In adults these rarer forms are usually partial and milder.
In plain terms: the adrenal gland enlarges because the brain keeps shouting for cortisol the gland cannot make.
The Adult Phenotype: Nonclassic 21-Hydroxylase Deficiency
Adults rarely present with the salt-wasting form, which appears in infancy with dehydration and shock. The adult type is nonclassic, meaning 20 to 50 percent residual enzyme activity. Cortisol production is usually adequate at rest, so there is no adrenal crisis unless the person is stressed or misdiagnosed and given suppressive therapy. The visible problem is androgen excess.
Typical adult findings cluster into a recognizable pattern:
- Hirsutism affecting 60 to 80 percent of affected women, often beginning in the teens
- Oligomenorrhea or amenorrhea in roughly half of affected women
- Acne that persists past age 25 or recurs after standard treatment
- Reduced fertility, sometimes the first presenting complaint
- Short stature relative to parental height, reflecting early epiphyseal closure
- Asymptomatic presentation in a meaningful minority, found only on genetic testing
Men with nonclassic disease are often entirely silent, though some show early puberty, testicular adrenal rest tissue, or reduced sperm counts. Because the male phenotype is subtle, many cases pass undiagnosed across a lifetime.
Why Adult Diagnosis Is Frequently Missed
Adult adrenal hyperplasia hides behind three common labels. The first is polycystic ovary syndrome. An estimated 1 to 10 percent of women diagnosed with PCOS actually have nonclassic congenital adrenal hyperplasia, depending on the population studied. The overlap in hirsutism and irregular cycles makes them nearly indistinguishable on clinical grounds alone. Distinguishing them requires a 17-hydroxyprogesterone level, which PCOS workups often skip.
The second label is idiopathic hirsutism. The third is simple acne. Both diagnoses delay genetic confirmation by years. A professional caveat worth stating plainly: a normal-looking ultrasound in a hirsute woman does not rule out adrenal hyperplasia, and an elevated testosterone mildly above the female reference range should prompt the enzyme test.
A second misconception concerns imaging. Adrenal enlargement on CT or MRI suggests hyperplasia, but a normal-sized gland does not exclude it. Many adults with nonclassic disease have glands within normal dimensions. Imaging is more useful for excluding adenoma or carcinoma than for confirming enzyme defects.
Diagnostic Thresholds and the ACTH Stimulation Test
The core test is serum 17-hydroxyprogesterone, drawn in the early morning follicular phase to avoid luteal variation. Basal values need careful interpretation. A morning level above 200 ng/dL warrants further testing. A value above 1,000 ng/dL is strongly suggestive of nonclassic disease in a symptomatic adult. Values between those thresholds require a cosyntropin stimulation test, with a 60-minute post-stimulation cutoff of 1,000 to 1,500 ng/dL depending on the assay.
The thresholds must be reconciled explicitly: a basal level above 200 ng/dL prompts stimulation, a peak above roughly 1,000 ng/dL after stimulation confirms the diagnosis, and a peak below 1,000 ng/dL makes it unlikely. Assay differences of 20 to 30 percent between laboratories mean borderline results should be repeated at a reference lab.
Genetic testing of the CYP21A2 gene confirms the diagnosis and guides family counseling. It is especially useful when biochemistry is ambiguous or when a partner is being screened before pregnancy.
| Test | Threshold | Meaning |
|---|---|---|
| Basal 17-OHP, morning | Below 200 ng/dL | Unlikely |
| Basal 17-OHP, morning | 200–1,000 ng/dL | Indeterminate, proceed to stimulation |
| Basal 17-OHP, morning | Above 1,000 ng/dL | Highly suggestive |
| Cosyntropin-stimulated 17-OHP | Above 1,000 ng/dL | Confirms nonclassic form |
| Cosyntropin-stimulated 17-OHP | Above 10,000 ng/dL | Suggests classic form |
| CYP21A2 genotyping | Two pathogenic variants | Confirms diagnosis, informs prognosis |
How the Condition Unfolds Over Time
Adrenal hyperplasia is lifelong, but its clinical expression shifts with age and hormonal state. The timeline below reflects the typical adult course for the nonclassic form.
| Age or Stage | Typical Event | Clinical Consequence |
|---|---|---|
| Childhood, 4–8 years | Pubarche may begin early | Mild virilization, advanced bone age |
| Adolescence | Hirsutism and acne emerge | Often attributed to puberty |
| Early adulthood, 18–25 years | Menstrual irregularity noted | PCOS label frequently applied |
| Reproductive years, 25–35 years | Fertility concerns prompt workup | Diagnosis often made here |
| Pregnancy | Androgen shift plus placental hormones | Symptoms may flare or improve |
| Perimenopause, 45–55 years | Ovarian androgen output falls | Hirsutism sometimes eases |
| Any age with major stress | Cortisol demand rises | Rare adrenal crisis in partial defects |
Pregnancy deserves special mention. The placenta produces progesterone that competes at the enzyme level, and some women with nonclassic disease first come to attention because of infertility or recurrent miscarriage. Treated pregnancies generally proceed normally, though glucocorticoid dosing needs review by an endocrinologist.
Treatment Choices and Their Trade-Offs
Treatment depends on symptoms, fertility goals, and the risk of overtreatment. Glucocorticoids suppress ACTH drive and reduce androgen output, but they carry their own burden. The table below compares the main options.
| Approach | Mechanism | Best For | Main Drawback |
|---|---|---|---|
| Low-dose hydrocortisone or prednisolone | Suppresses ACTH, lowers androgen precursors | Symptomatic women not seeking pregnancy | Bone loss, weight gain at higher doses |
| Combined oral contraceptive | Suppresses ovarian and adrenal androgen output | Hirsutism with cycle control | Masks fertility, no effect on enzyme defect |
| Anti-androgen such as spironolactone | Blocks androgen receptor | Hirsutism refractory to steroids | Contraindicated in pregnancy |
| Ovulation induction with letrozole or clomiphene | Restores ovulation | Infertility | Does not correct underlying enzyme defect |
| Cosmetic and laser therapy | Removes hair directly | Local hirsutism | Recurrence without hormonal control |
| No treatment with monitoring | Avoids medication burden | Asymptomatic adults | Unclear long-term risk in some cases |
Hydrocortisone at 10 to 15 mg per square meter per day, divided into two or three doses, is the standard starting range for adults who need glucocorticoid suppression. Overtreatment is the common error. Doses that fully normalize 17-hydroxyprogesterone often cause iatrogenic Cushing features within 12 to 24 months. The goal is symptom control with the lowest effective dose, not biochemical perfection.
What to Actually Do If You Suspect It
A practical sequence cuts years off the diagnostic delay:
- Ask for a morning 17-hydroxyprogesterone level before starting any hormonal contraception, which can alter results.
- If the level is borderline, request a cosyntropin stimulation test rather than repeating the same basal test.
- Bring a menstrual and fertility history to the visit, since timing of symptoms matters