Adrenal hyperplasia is an overgrowth of the adrenal glands that occurs when they can’t produce enough of certain hormones, most commonly cortisol. The brain responds to low cortisol by sending stronger and stronger signals to the adrenal glands, demanding more output. This constant stimulation causes the glands to enlarge. The most common form, congenital adrenal hyperplasia (CAH), affects roughly 1 in 15,000 newborns worldwide and is present from birth. Other, rarer forms develop later in life and involve abnormal nodules growing on the adrenal glands.
How the Adrenal Glands Become Overgrown
Your two adrenal glands sit on top of your kidneys and produce three important classes of hormones: cortisol (which manages stress and blood sugar), aldosterone (which controls salt and water balance), and androgens (sex hormones). The raw material for all of these is cholesterol, which gets converted through a chain of enzyme-driven steps into whichever hormone is needed.
Cortisol production is controlled by a feedback loop between the brain and the adrenal glands. When cortisol levels drop, the brain’s pituitary gland releases a hormone called ACTH that tells the adrenals to make more. Once cortisol rises, the brain eases off. In adrenal hyperplasia, a genetic mutation disables one of the enzymes in the cortisol production chain. Cortisol never reaches adequate levels, so the brain never gets the signal to stop. ACTH keeps flooding the adrenal glands, and the constant stimulation causes them to grow larger and larger.
The enzyme blockage doesn’t just reduce cortisol. The chemical precursors that were supposed to become cortisol pile up with nowhere to go, and the adrenal glands shunt them down an alternate pathway, converting them into androgens instead. This is why excess male sex hormones are a hallmark of the condition, even in females.
Congenital Adrenal Hyperplasia (CAH)
CAH is by far the most common type of adrenal hyperplasia. It’s a genetic condition inherited in an autosomal recessive pattern, meaning a child must receive a defective gene copy from both parents to be affected. About 95% of CAH cases involve a deficiency of an enzyme called 21-hydroxylase. Without this enzyme, the adrenal glands can’t properly produce cortisol or aldosterone, and androgen levels climb.
The severity depends on how much enzyme activity remains, and doctors classify CAH into three forms based on this:
- Salt-wasting (less than 1% enzyme activity): The most severe form. Both cortisol and aldosterone are critically low. Aldosterone deficiency means the body can’t retain sodium, leading to dangerous salt loss, dehydration, and potentially life-threatening adrenal crisis in the first weeks of life.
- Simple virilizing (1 to 2% enzyme activity): Cortisol is low and androgens are high, but aldosterone production is sufficient enough to prevent severe salt loss. The primary concern is the effect of excess androgens on development.
- Non-classical (20 to 60% enzyme activity): The mildest form. Symptoms may not appear until adolescence or adulthood, and some people never know they have it.
Symptoms in Newborns and Infants
In the salt-wasting form, sodium loss and potassium buildup can be detected in blood tests as early as four to seven days after birth, though visible symptoms typically appear during the second to fourth week of life. These babies may develop poor feeding, vomiting, weight loss, dehydration, and lethargy. Without treatment, the salt imbalance can progress to shock. Skin hyperpigmentation and low blood sugar are also common early signs.
Excess androgens during fetal development can significantly affect genital anatomy. Genetic females with severe CAH may be born with genitalia that appear more typically male, while internal reproductive organs develop normally. In genetic males, the changes are subtler and CAH is often missed at birth, which is why newborn screening programs that test hormone levels in the first days of life are so important for early detection.
Symptoms in Older Children and Adults
In the simple virilizing form, children who weren’t identified through newborn screening may show signs of early puberty, rapid growth in childhood followed by a shorter-than-expected adult height, severe acne, and body hair appearing earlier than normal. These effects come from the chronic excess of androgens.
Non-classical CAH often goes undiagnosed until a person seeks help for symptoms that overlap heavily with polycystic ovary syndrome (PCOS). Women may experience excess facial and body hair, acne, thinning hair on the scalp, irregular periods, and difficulty getting pregnant. Men with non-classical CAH are frequently diagnosed only during family screening after a relative is identified.
Bilateral Adrenal Hyperplasia in Adults
Not all adrenal hyperplasia is congenital. In adults, the adrenal glands can develop abnormal nodular growth on both sides, leading to excess cortisol production and Cushing’s syndrome. These forms are rarer and fall into two main categories.
Primary bilateral macronodular adrenal hyperplasia (PBMAH) involves nodules larger than 1 centimeter on both adrenal glands. What makes this form unusual is that the nodules themselves can produce ACTH locally, meaning the glands are essentially stimulating their own growth. Most people with PBMAH have subtle, slowly progressing cortisol excess that may go unnoticed for years. Symptoms include gradual weight gain (particularly around the midsection and face), easy bruising, high blood pressure, and thinning skin.
Micronodular forms, including a condition called primary pigmented nodular adrenocortical disease, involve smaller nodules under 1 centimeter. These tend to appear in younger patients and can cause either obvious or subtle cortisol excess. Both macronodular and micronodular forms ultimately lead to Cushing’s syndrome if untreated.
Adrenal Crisis: The Most Serious Risk
People with CAH who can’t make enough cortisol are vulnerable to adrenal crisis, a medical emergency that occurs when the body faces a physical stress (illness, surgery, injury) it can’t mount a proper hormonal response to. Early symptoms are easy to miss: fatigue, nausea, vomiting, abdominal pain, dizziness, and confusion. These can rapidly escalate to dangerously low blood pressure and altered consciousness.
What makes adrenal crisis particularly dangerous is that the low blood pressure doesn’t respond to standard treatments like IV fluids alone. It requires prompt hormone replacement to stabilize. People with known CAH learn to carry emergency medication and increase their daily hormone doses during illness, often called “stress dosing,” to prevent a crisis from developing.
How CAH Is Managed
Treatment for CAH centers on replacing the hormones the body can’t make and suppressing the overproduction of androgens. For the classical (more severe) forms, this means taking a daily glucocorticoid, typically hydrocortisone in children, to replace cortisol. The replacement also signals the brain to stop overdriving the adrenal glands, which brings androgen levels down.
People with the salt-wasting form also need a mineralocorticoid to help the body retain sodium. Infants usually require additional salt supplementation mixed into their feedings during the first months of life, since breast milk and formula alone don’t provide enough sodium to compensate for the loss.
Non-classical CAH doesn’t always require treatment. When it does, lower glucocorticoid doses are used, primarily to manage androgen-related symptoms like acne, excess hair growth, or menstrual irregularity. Treatment is tailored to the individual’s symptoms and goals rather than following a one-size-fits-all protocol.
Management is lifelong for classical CAH. Regular blood work monitors hormone levels and medication is adjusted during growth spurts, illness, and other periods of physical stress. The goal is a careful balance: enough glucocorticoid to control androgens and prevent adrenal crisis, but not so much that it causes the side effects of excess cortisol, including weight gain, bone thinning, and slowed growth in children.
Fertility and Family Planning
Fertility is a significant concern for people with CAH, particularly women. Excess androgens can interfere with ovulation by disrupting the normal hormonal signals that trigger egg release each month. Elevated levels of adrenal-derived progesterone can also thin the uterine lining, impair sperm penetration, and make implantation more difficult. The result is that women with CAH, including non-classical forms, face higher rates of delayed conception and miscarriage compared to the general population.
Many women with non-classical CAH can conceive without medical assistance, but those who struggle often benefit from adjusting their glucocorticoid treatment to bring progesterone to target levels during the follicular phase of their cycle. The symptoms and fertility challenges overlap so closely with PCOS that some women are initially treated for the wrong condition.
Genetic counseling is strongly recommended for anyone with CAH who is planning a pregnancy. Because the condition is autosomal recessive, the partner’s carrier status determines the risk to the child. Genotyping both partners can clarify whether future children could be affected and, if so, how severe the form might be. This information allows families to plan ahead and ensures that newborns who may need immediate treatment are identified quickly.