The Adrenal Glands: Small but Mighty...

By Zeina A. Habib, MD

What are the adrenal glands?

The adrenals are two small glands that look like mushroom caps. One adrenal gland sits above each kidney. These glands are 1-2 inches long and weigh only 1.5-2.5 grams. Even though they are small, the adrenal glands are very important. They make several hormones that are needed for well being and normal body functioning. The adrenal hormones play a major role in regulating metabolism and immunity; maintaining blood pressure, body water and minerals; and helping the body respond and adapt to stress.

What are the adrenal hormones?

What are their functions?

Each adrenal gland is made up of a large outer zone—the adrenal cortex, and a small inner zone—the adrenal medulla.

The adrenal cortex produces three different kinds of hormones: glucocorticoids [gloo-koh-KAWR-ti-koids], mineralocorticoids [min-er-uh-loh-KAWR-ti-koids], and androgens.

Cortisol

Cortisol is the major glucocorticoid. It regulates glucose, fat, and proteins and helps keep the body’s metabolism in check. Cortisol is important in regulating blood pressure. It also plays a role in controlling inflammation, and, by its action on the brain, has an effect on emotion and perception. The pituitary [pi-TOO-i-ter-ee] gland in the brain controls cortisol production.

Aldosterone

Aldosterone [al-DOS-tuh-rohn] is the major mineralocorticoid. Its main function is to regulate sodium and potassium balance, as well as blood pressure.

Androgens

Androgens cause some of the changes seen in puberty, such as growth of pubic and underarm hair, body odor, and acne.

The adrenal medulla [muh-DUHL-uh] produces a family of hormones known as catecholamines [kat-i-KOL-uh-meens].

Catecholamines

Catecholamines, such as adrenaline [uh-DREN-l-in], cause the “fight or flight” response. They also help mobilize sources of energy, since energy is needed in coping with stressful situations.

What happens if the adrenal glands are producing too many hormones? How can these be treated?

Cortisol excess

Too much cortisol can cause Cushing’s syndrome. This is usually because of a tumor in the adrenal gland or pituitary glands. Signs and symptoms of Cushing’s syndrome include the following:

  • weight gain
  • round or “moon-like” face
  • fat in the back of the neck (called a “buffalo hump”)
  • purple stretch marks on the belly
  • lack of or fewer menstrual periods
  • muscle weakness
  • thinning of the skin and bones
  • high blood pressure
  • high blood sugars, and
  • depression.

People who take steroids for a long time can also get Cushing’s syndrome. In most cases of Cushing’s syndrome from an adrenal or pituitary tumor, the tumor will need to be removed.

Aldosterone excess

Too much aldosterone can be produced by both adrenal glands or by a tumor in one of the adrenal glands. This can cause high blood pressure and sometimes low potassium levels.

If a tumor is found, it will usually have to be removed by surgery. In patients who do not have a tumor, and those who cannot or are not willing to go through surgery, too much aldosterone can be treated with medication.

Androgen excess

Too much androgen is usually caused by a genetic condition (congenital adrenal hyperplasia [hy-per-PLAY-zhuh]), or to an adrenal cancer. Congenital adrenal hyperplasia is the result of a lack of enzymes that are necessary for cortisol and aldosterone to be produced. Because of the lack of enzymes, the adrenal glands will make less cortisol and aldosterone and more androgens. This disorder is sometimes diagnosed at birth in girls who may have genitals that aren’t clearly male or female. Sometimes this disorder is diagnosed later in life around puberty. Too much androgen in females causes excess facial hair, acne, and deepening of the voice. The condition is usually treated with corticosteroids [kor-tih-koh-STER-oids]. Adrenal cancer is rare. In some cases, adrenal cancer can produce excess androgens. This results in acne, excess hair growth, and decreased/absent menstrual cycles in females. Adrenal cancer is treated with surgery when possible, and in some cases additional medications, chemotherapy, or radiation are needed.

Catecholamine excess

An adrenal tumor that produces excess catecholamines [kat-i-KOL-uh-meens], is known as a pheochromocytoma [fee-oh-kroh-moh-sahy-TOH-muh]. These types of tumors are rare. Even though most of these tumors are not cancerous, it is very important to test for this condition. High levels of catecholamines can cause a dangerous rise in blood pressure. Symptoms include headaches, sweating, palpitations, paleness or flushing, and elevated blood pressure. These symptoms aren’t always present. The high blood pressure may be continuous or periodic. Once blood pressure is controlled, these tumors can be treated by surgery.

What happens if the adrenal glands are not producing enough hormones? How can this be corrected?

Adrenal insufficiency [in-suh-FISH-uhn-see], or not enough cortisol, can be from a disorder in the adrenal gland itself. Such a disorder can be caused by the immune system going haywire and destroying the adrenal glands. It can also be caused by bleeding or infection in the adrenal glands. This condition usually goes hand in hand with aldosterone deficiency. Symptoms include fatigue, weakness, dizziness, and low blood pressure. These symptoms can sometimes be severe. Treatment involves replacing the lack of hormones. Adrenal insufficiency can also be caused by the pituitary gland failing to stimulate cortisol production by the adrenal glands. In the majority of these cases, aldosterone production is sufficient. It is usually treated by giving corticosteroid hormones to replace cortisol.

What is an adrenal incidentaloma?

An adrenal incidentaloma [in-sih-den-tah-LOH-mah] is an adrenal tumor that is found unexpectedly during a CT scan (“CAT scan”). Adrenal incidentalomas are found in about 4% of CT scans. When one of these tumors is found, it is important to make sure that it is not cancerous and/or is not producing excess hormones. Cancerous tumors look different than non-cancerous tumors. Blood or urine tests can check for excess hormone production. Adrenal tumors that appear not to be cancerous or hormone-producing can be watched, but those that are cancerous or are producing excess hormones usually need to be removed by surgery.

Dr. Zeina Habib is a fellow in Endocrinology at Loyola University Medical Center. She graduated from the American University of Beirut Medical School, Lebanon. She completed her post-graduate training in Internal Medicine at Henry Ford Hospital, Detroit, where she also served as a Chief Medical Resident. Dr. Habib’s clinical interests include adrenal disorders and bone and mineral abnormalities. She conducted research on vitamin D deficiency and fracture risk in patients with diabetes. Her studies were published in peer-reviewed medical journals such as Endocrine Practice and The Journal of Clinical Endocrinology and Metabolism.