Adrenal hyperplasia refers to the enlargement of the adrenal glands caused by a disruption in their ability to produce certain hormones, most commonly cortisol. The vast majority of cases are inherited, falling under the umbrella term congenital adrenal hyperplasia (CAH), a group of genetic conditions where enzyme deficiencies in the adrenal glands force them to overproduce androgens (sometimes called “male hormones,” though everyone makes them) while underproducing cortisol and, in severe cases, aldosterone. The condition ranges from life-threatening salt-wasting crises in newborns to mild androgen excess that may not be noticed until adulthood, and it has implications for growth, fertility, and long-term metabolic health that extend well beyond the adrenal glands themselves.
Why the Adrenal Glands Enlarge in the First Place
Your adrenal glands sit on top of your kidneys and manufacture several critical steroid hormones, including cortisol (a stress hormone), aldosterone (which regulates salt and water balance), and androgens. When a genetic mutation disables one of the enzymes needed to make cortisol, the brain’s pituitary gland senses low cortisol levels and responds by sending more and more of a stimulating signal called ACTH. That relentless stimulation causes the adrenal tissue to grow larger, hence “hyperplasia,” and the blocked hormone-production pathway gets diverted toward androgens instead. The result is a double problem: not enough cortisol (and sometimes not enough aldosterone) combined with too many androgens.
About 95% of all CAH cases trace back to a deficiency of a single enzyme called 21-hydroxylase, encoded by the CYP21A2 gene.1PubMed Central. Rare Types of Congenital Adrenal Hyperplasias Other Than 21-hydroxylase Deficiency The remaining cases involve other enzyme deficiencies, such as 11-beta-hydroxylase deficiency, 3-beta-hydroxysteroid dehydrogenase deficiency, or 17-hydroxylase deficiency, each of which produces a somewhat different hormonal profile and set of symptoms.2PubMed. Rare forms of congenital adrenal hyperplasia Because 21-hydroxylase deficiency is so overwhelmingly common, when clinicians say “CAH” without further qualification, they almost always mean this form.
How the Genetic Mutations Work
CAH follows an autosomal recessive inheritance pattern, meaning a child needs to inherit a faulty copy of the gene from each parent to develop the condition. Carriers who have only one faulty copy typically produce enough enzyme to avoid symptoms. The CYP21A2 gene sits very close on the chromosome to a nearly identical but nonfunctional “pseudogene” called CYP21P. During cell division, these two similar sequences can swap material with each other in a process called recombination. More than 90% of the disease-causing mutations arise from these recombination events: roughly a fifth are outright gene deletions, while the rest involve harmful sequences from the pseudogene being copied into the working gene.3Endocrine Reviews. Congenital Adrenal Hyperplasia due to 21-Hydroxylase Deficiency
How badly any given mutation cripples the enzyme is closely linked to how severe the disease ends up being. Mutations that wipe out nearly all enzyme activity lead to the most severe “classic” forms, while milder mutations that leave some enzyme function intact lead to the milder “non-classic” form. This means genetic testing can often predict, at least roughly, how a person’s disease will manifest.
Classic CAH and Its Two Faces
Classic CAH is the severe end of the spectrum. It affects roughly one in 15,000 births and is further divided into two subtypes based on whether aldosterone production is also severely impaired.
Salt-Wasting CAH
About three-quarters of classic CAH cases are the salt-wasting form. These babies cannot make adequate aldosterone, so their kidneys lose dangerous amounts of sodium. Without treatment, this leads to dehydration, dangerously low blood sodium, high potassium, and potentially fatal cardiovascular collapse, sometimes called an adrenal crisis or salt-wasting crisis. Symptoms often appear within the first one to three weeks of life and can include poor feeding, vomiting, lethargy, and failure to gain weight.4PubMed Central. Salt-Wasting Form of Congenital Adrenal Hyperplasia: A Case Report Case reports describe newborns presenting with severe electrolyte imbalances and life-threatening heart rhythm disturbances as early as ten days old.5PubMed Central. Congenital adrenal hyperplasia with salt-wasting crisis and arrhythmia: a case study If CAH is not identified and treated early, infants are at risk of sudden death in the first weeks of life.6PubMed Central. Congenital Adrenal Hyperplasia with Salt Wasting Crisis: A Case Report
In genetic females, the androgen excess that begins before birth causes ambiguous genitalia at birth, which often prompts earlier medical evaluation. In genetic males, the external genitalia may look normal, meaning the salt-wasting crisis can arrive without any prior warning, making boys statistically more vulnerable to a delayed diagnosis.
Simple-Virilizing CAH
The remaining quarter of classic cases are called “simple-virilizing.” These individuals produce enough aldosterone to avoid salt-wasting crises, but they still overproduce androgens. In girls, this again causes ambiguous genitalia at birth. In boys, the condition may go unrecognized until childhood, when signs of early puberty start appearing, such as rapid growth, pubic or underarm hair well before the expected age, acne, and deepening of the voice. One case report describes a 13-year-old who was assigned female at birth presenting with primary amenorrhea, male-pattern hair growth, and a progressively deepening voice, and was ultimately diagnosed with simple-virilizing CAH after further testing revealed markedly elevated 17-hydroxyprogesterone.7PubMed Central. Challenges in the Diagnosis of Simple-Virilizing Congenital Adrenal hyperplasia: A Case Report
Non-Classic CAH
Non-classic CAH (sometimes called late-onset CAH) is considerably more common than the classic forms, affecting an estimated one in 200 to one in 1,000 people depending on the population. The enzyme still works, just not at full capacity, so cortisol production is reduced but not absent, and aldosterone is generally fine. There is no salt-wasting risk and no ambiguous genitalia at birth.
Instead, symptoms show up later, during childhood, adolescence, or adulthood, and are driven by mild-to-moderate androgen excess. In women and girls, the most common complaints include acne, excess body and facial hair (hirsutism), irregular or absent menstrual periods, and thinning scalp hair.8PubMed. Non-classic congenital adrenal hyperplasia In men, non-classic CAH may cause early beard growth or acne but frequently goes undiagnosed because male androgen excess is less socially conspicuous. Some people with non-classic CAH never develop noticeable symptoms and are only identified through family screening after a relative is diagnosed with a more severe form.
Telling Non-Classic CAH Apart from PCOS
One of the practical challenges with non-classic CAH in women is that its symptoms look almost identical to polycystic ovary syndrome (PCOS), a far more common condition. Both can cause irregular periods, hirsutism, acne, and difficulty conceiving. The key screening test to distinguish them is measuring 17-hydroxyprogesterone (17-OHP) levels; if baseline levels are borderline, an ACTH stimulation test can separate the two conditions, because women with non-classic CAH show a much sharper rise in 17-OHP after stimulation than women with PCOS.9PubMed Central. Polycystic Ovary Syndrome and NC-CAH: Distinct Characteristics and Common Findings. A Systematic Review
Beyond hormones, the two conditions also diverge metabolically. Research comparing women with non-classic CAH to women with PCOS found that those with PCOS tend to have higher body mass index, greater insulin resistance, higher triglycerides, and lower HDL cholesterol, while women with non-classic CAH have much higher 17-OHP and 21-deoxycortisol levels but a less unfavorable metabolic profile.10Karbala Journal of Pharmaceutical Sciences. Adrenal–Metabolic Biomarker Panel for Differentiating Non-Classic Congenital Adrenal Hyperplasia from Polycystic Ovary Syndrome in Women with Hyperandrogenic Features Getting the distinction right matters because the treatments differ: PCOS management centers on insulin sensitizers and oral contraceptives, while non-classic CAH may call for low-dose glucocorticoids.
Newborn Screening and Diagnosis
Most developed countries now include CAH on their newborn screening panels. The test measures 17-OHP levels from a heel-prick blood spot collected in the first days of life. The screening works well for classic CAH but is not designed to catch non-classic cases, which have lower 17-OHP levels. False positives are a recognized issue, particularly in premature or stressed newborns, whose 17-OHP levels can be transiently elevated by other steroid compounds in the blood. Laboratories use techniques such as ether extraction to separate 17-OHP from interfering polar steroids and reduce false alarms.11PubMed. False positive rate in newborn screening for congenital adrenal hyperplasia (CAH)-ether extraction reveals two distinct reasons for elevated 17alpha-hydroxyprogesterone (17-OHP) values
For older children and adults suspected of having non-classic CAH, the diagnostic workup typically begins with a morning blood draw for 17-OHP, followed by ACTH stimulation testing if levels are borderline. Genetic testing of CYP21A2 can confirm the diagnosis and help predict disease severity. Imaging is not routinely needed for diagnosis but may be ordered to rule out adrenal tumors when the hormonal picture is atypical.
Fertility Concerns
Fertility is one of the areas where CAH’s impact extends well into adulthood, and the picture differs for women and men.
Women with CAH
In women with non-classic CAH, subfertility is generally mild. A large study of 190 women who wanted to conceive found that 85 of them achieved a total of 187 pregnancies. About 83% of pregnancies were obtained within one year. However, the miscarriage rate was significantly lower in women who conceived while on glucocorticoid treatment (about 7%) compared with those who conceived without it (about 26%), which argues for treating women with non-classic CAH when they are trying to become pregnant.12PubMed. Fertility in women with nonclassical congenital adrenal hyperplasia due to 21-hydroxylase deficiency Additional research has confirmed that higher androgen levels and longer time-to-conception both correlate with increased miscarriage risk, and that glucocorticoid treatment helps by lowering androgens and shortening the time to conception.13PubMed. Fertility and pregnancy outcomes in women with nonclassic 21-hydroxylase deficiency
Women with classic CAH face greater fertility challenges, related to more severe hormonal imbalances, possible anatomical factors from genital surgery, and the complex effects of lifelong glucocorticoid therapy. Spontaneous conception is still possible but often requires careful hormonal management.
Men with CAH
Male fertility in CAH is threatened by a complication called testicular adrenal rest tumors (TARTs). These are benign growths of adrenal-like tissue within the testicles, left over from embryonic development, that enlarge under the influence of high ACTH levels. In one study of adult men with CAH, TARTs were found in 86% of participants, and fertility was significantly impaired, with affected men having an average of 0.9 children compared with a national average of 1.8. Semen analysis was abnormal in 43% of those tested, with sperm concentration correlating with markers of testicular function.14PubMed Central. Fertility, sexuality and testicular adrenal rest tumors in adult males with congenital adrenal hyperplasia TARTs can appear as early as childhood and are typically monitored with ultrasound.15PubMed Central. Testicular adrenal rest tumours in congenital adrenal hyperplasia Optimizing glucocorticoid therapy to suppress ACTH can sometimes shrink these tumors, but in advanced cases the damage to surrounding testicular tissue may be irreversible.
Treatment with Glucocorticoids and Mineralocorticoids
The cornerstone of CAH treatment since 1950 has been replacing the cortisol the body cannot make on its own, using synthetic glucocorticoids such as hydrocortisone, prednisone, or dexamethasone.16PubMed. A Brief History of Congenital Adrenal Hyperplasia By supplying cortisol from outside, the treatment tells the pituitary to stop sending excessive ACTH, which in turn reduces the adrenal overgrowth and the androgen overproduction. Patients with the salt-wasting form also need a mineralocorticoid (fludrocortisone) to replace missing aldosterone, along with salt supplementation in infancy.
The problem is that glucocorticoids are a blunt instrument. The body naturally releases cortisol in a pulsatile, circadian pattern, with a peak in the early morning and a trough at night. Standard oral tablets cannot replicate this rhythm well. A dose high enough to suppress androgens around the clock often overshoots at certain times of day, exposing the body to more glucocorticoid than it needs. Over years and decades, this supraphysiological exposure contributes to weight gain, poor bone health, cardiovascular risk, and metabolic problems.17PubMed Central. Novel treatment strategies in congenital adrenal hyperplasia A study of young children with CAH found that those receiving hydrocortisone in a liquid suspension form had significantly less bone-age advancement than those on crushed tablets, suggesting that even the formulation of the medication can affect outcomes in growing children.18Journal of the Endocrine Society. Bone Age Maturation and Growth Outcomes in Young Children with CAH Treated with Hydrocortisone Suspension
Balancing androgen control against glucocorticoid side effects is the central tension of CAH management. Clinicians monitor 17-OHP, androstenedione, testosterone, and growth velocity to try to find the lowest effective dose, but the therapeutic window is narrow, and many patients spend years swinging between under-treatment (high androgens, accelerated bone aging, early puberty) and over-treatment (excess weight, growth suppression, metabolic harm).
Crinecerfont and the Shift Toward Targeted Therapy
The biggest treatment advance in decades is crinecerfont, a drug that works by blocking the receptor for corticotropin-releasing hormone (CRH), the brain signal that ultimately drives ACTH release. By intercepting the signal upstream, crinecerfont lowers ACTH and androgens without requiring higher glucocorticoid doses. In a phase II trial in adolescents, two weeks of crinecerfont cut ACTH by about 57%, 17-OHP by about 69%, and androstenedione by about 58%.19PubMed Central. Crinecerfont, a CRF1 Receptor Antagonist, Lowers Adrenal Androgens in Adolescents With Congenital Adrenal Hyperplasia
Phase III trials went further, showing that crinecerfont allowed glucocorticoid doses to be reduced by about 27% in adults and 18% in children while still keeping androgens controlled. Testosterone levels dropped by 32% to 74% in adults and 61% to 76% in pediatric participants during phase II.20PubMed. Crinecerfont: CRF1R Antagonist Approved for Treatment of Congenital Adrenal Hyperplasia This is a meaningful step because it directly addresses the core problem of CAH management: you can now lower the glucocorticoid burden without losing androgen control.21PubMed. CRH receptor antagonist crinecerfont – a promising new treatment option for patients with congenital adrenal hyperplasia due to 21-hydroxylase deficiency Other experimental approaches are also in development, including modified-release glucocorticoid formulations designed to mimic the body’s natural cortisol rhythm and continuous subcutaneous hydrocortisone pumps.
Genital Surgery in Classic CAH
For girls born with ambiguous genitalia due to classic CAH, the question of genital reconstructive surgery has been one of the most debated topics in pediatric endocrinology and surgery. Procedures may include clitoroplasty (reduction of an enlarged clitoris) and vaginoplasty (creation or widening of a vaginal opening), performed in one or two stages.
A systematic review of long-term outcomes found that after an average follow-up of about ten years, most women who had undergone surgery identified as female (about 89%) and were heterosexual (about 76%). Sexual function scores averaged about 25 out of a maximum 36 on a standard index, and while most patients were sexually active, only about half reported comfortable intercourse. Vaginal stenosis (narrowing) was a common long-term complication, occurring in about 27% of cases, and many women reported reduced clitoral sensitivity.22The Journal of Clinical Endocrinology & Metabolism. Genital Reconstructive Surgery in Females With Congenital Adrenal Hyperplasia: A Systematic Review and Meta-Analysis Another study following patients from infancy into adulthood found that six out of seven who had a single-stage procedure as infants required repeat vaginoplasty at puberty, and vaginal strictures persisted in three out of five examined.23PubMed. The long term outcome of feminizing genital surgery for congenital adrenal hyperplasia
These outcomes have fueled growing debate. Some medical bodies and patient advocacy groups argue that non-urgent surgery should be deferred until the individual is old enough to participate in the decision, while others maintain that early surgery reduces psychosocial distress for the child and family. There is no consensus, and practices vary across countries and institutions. What is clear from the data is that surgery frequently requires revision and carries lasting effects on sexual function and sensation, which every family considering it should know.
Psychosocial Dimensions and Identity
Prenatal androgen exposure in classic CAH has measurable effects on behavior and interests that go beyond the physical. Research comparing women with classic CAH, non-classic CAH, and unaffected controls found that women with classic CAH showed friendship patterns and occupational choices more aligned with male controls than female controls, while women with non-classic CAH responded similarly to unaffected women on most measures. The severity of CAH correlated with the degree of this shift: more severe forms were associated with responses more in line with male norms.24PubMed. Gendered interests and behavior in women with congenital adrenal hyperplasia or complete androgen insensitivity syndrome
Qualitative research with women who have CAH has found that experiences of identity formation vary widely. Some described CAH as a central feature of their lives, while others treated it as a side issue. Themes around “forming identity” (as a girl, a tomboy, a woman) and “establishing relationships” (navigating intimacy, pregnancy, parenthood) emerged as major threads, with perspectives shifting over the course of their lives.25Journal of Pediatric and Adolescent Gynecology. Identity, Sexuality, and Parenthood in Women with Congenital Adrenal Hyperplasia These findings underscore that CAH is not just a hormonal condition but one that can shape a person’s sense of self in complex ways, particularly for those with the classic form.
Acquired Forms of Adrenal Hyperplasia
Not all adrenal hyperplasia is congenital. A separate condition called bilateral macronodular adrenal hyperplasia (BMAH) develops in adulthood and causes the adrenal glands to enlarge with large nodules. Unlike CAH, BMAH is not caused by a single inherited enzyme deficiency. Instead, the adrenal tissue itself begins producing ACTH locally, creating a feedback loop that drives further growth and cortisol overproduction, sometimes leading to Cushing’s syndrome. Research has shown that the locally produced ACTH in BMAH responds to signals from abnormal hormone receptors on the adrenal cells, rather than to the normal brain-derived CRH signal.26PubMed. Intraadrenal corticotropin in bilateral macronodular adrenal hyperplasia This discovery has opened up potential avenues for medical treatment by targeting those aberrant receptors.27PubMed. Primary bilateral macronodular adrenal hyperplasia BMAH is rare and typically diagnosed incidentally when imaging is done for another reason, or when signs of cortisol excess prompt further investigation. Its treatment may involve surgery to remove one or both adrenal glands, or medical management aimed at controlling cortisol production.