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Updated on May 10, 2024
Congenital adrenal hyperplasia (CAH) is a group of genetic disorders that affect the adrenal glands, a pair of walnut-sized glands that are located on the kidneys. These small glands are part of the body’s endocrine system, the network of organs and tissues that produce and release hormones.
Hormones are chemical messengers that travel through the bloodstream and regulate hundreds of different biological processes. The adrenal glands produce and release hormones that help regulate metabolism, blood pressure, immunity, growth and development, stress response, and more.
People who have CAH have a deficiency in an enzyme that the adrenal glands need in order to produce hormones, including cortisol, aldosterone, and androgens.
Cortisol
Cortisol is sometimes called the “stress hormone” because extra cortisol is released during stressful situations. This extra release of cortisol can help a person remain alert and respond when they are in a stressful situation. Cortisol helps a person respond to stress by increasing the amount of glucose (the body’s primary source of energy) in the bloodstream and brain, and also slows any functions that are nonessential during a stressful situation, such as immunity and digestion.
But cortisol has many more essential functions beyond its role in the body’s stress response—it helps regulate blood pressure, blood glucose levels, metabolism (the conversion of nutrients into energy), and inflammation.
Aldosterone and androgens
Cortisol is not the only hormone made by the adrenal glands. These glands also produce hormones called aldosterone and androgens:
- Aldosterone. This hormone helps the body maintain a healthy balance of fluids and the electrolytes sodium and potassium. Nerve signaling, muscle contraction, and normal fluid levels all depend on a balance of electrolytes.
- Androgens. These are male sex hormones, which support the growth and development of male sex characteristics, but they play an important role in the growth and development of males and females, including reproductive health.
Hormone synthesis
The adrenal glands synthesize hormones from cholesterol, a waxy, fat-like substance found in all cells throughout the body and in the blood. Hormone synthesis is a complex and multistep process that involves multiple enzymes, substances that start or speed up a chemical change.
Enzymes break down cholesterol into components. Those components come into contact with other enzymes and get converted into new substances. At one end of this process you have cholesterol, and at the other you should have hormones. (Keep in mind that this is a simplified explanation).
Hormone imbalance
People who have CAH lack enough of the enzymes that are needed to fully synthesize cortisol and/or aldosterone, which creates an imbalance of hormones. The lack of enzymes is caused by genetic mutations that are passed on from a person’s biological parents. The type of CAH a person has depends on the type of genetic mutation they have inherited and the severity of the enzyme deficiency:
- Salt-wasting classic CAH. This is the most severe type. People with this type have dangerously low levels of aldosterone. As a result, the body cannot retain enough sodium, which can lead to life-threatening complications. This type can also cause virilization symptoms, the development of exaggerated male sex characteristics. These symptoms are caused by too little cortisol, which results in an overproduction of androgens. This type is typically diagnosed shortly after a person is born.
- Simple virilizing classic CAH. This type is less severe, and the body will have enough aldosterone to maintain healthy sodium levels. This type will also cause virilization symptoms and is also typically diagnosed shortly after a person is born.
- Non-classic CAH. This is the most common type of CAH and is less severe than the classic types. A person with this type may have no symptoms, or mild virilization symptoms.
Additionally, there are rare types of CAH that are much less common than the types discussed here.
