Adrenal glands are hormone-producing organs divided into two parts. The inner part is the adrenal medulla, and the outer part is the adrenal cortex. The hormones produced by the adrenal glands regulate important functions in the body, such as blood pressure. Certain conditions can cause an imbalance in adrenal hormones.
Structure and Function
The body's two adrenal glands are in the upper region of the kidneys. Each gland is triangular and weighs up to 6 g in an adult. The adrenal medulla makes a class of hormones called catecholamines. The adrenal cortex makes more than one class of hormones--it produces corticosteroids, androgens and mineralocorticoids.
Hormones
Cortisol and aldosterone are hormones made in the adrenal cortex. Cortisol is a corticosteroid hormone that helps regulate blood pressure, blood sugar levels and inflammation. It also helps the body cope with stressful conditions such as illness. Aldosterone belongs to the mineralocorticoid class of hormones. It regulates the amount of sodium the body retains and how much potassium the body excretes. Through this, it affects the body's blood volume and blood pressure. Epinephrine, or adrenaline, is a catecholamine hormone that gets the body ready for action and regulates functions such as sweat production and heart rate.
Adrenal Glands and The Brain
The pituitary gland, found in the brain, releases several hormones, including a hormone called corticotropin. This hormone is also referred to as adenocorticotropic hormone, or ACTH. ACTH stimulates the adrenal glands to produce cortisol. When cortisol levels get too high, the pituitary gland reduces ACTH production, which in turn leads to a reduction in adrenal production of cortisol.
Underactive Adrenal Glands
When the adrenal glands are underactive, adrenal insufficiency occurs. If the condition is caused by damage to the adrenal glands, it's called Addison's disease. When it's caused by low ACTH levels due to problems with the pituitary gland, the condition is referred to as secondary adrenal insufficiency. Some signs of adrenal insufficiency are fatigue that worsens over time, weight loss and weakness in the muscles. The National Endocrine and Metabolic Diseases Information Service reports that Addison's disease affects 1 to 4 of every 100,000 people, regardless of age or sex.
Hyperactive Adrenal Glands
When the adrenal glands are hyperactive, overproduction of the adrenal hormones occurs. This may be due to a catecholamine-secreting tumor in the adrenal medulla called a pheochromocytoma. Tumors in other areas of the adrenal gland can also cause overproduction of cortisol and the other adrenal hormones.
Too much cortisol leads to Cushing's syndrome, a disease characterized by a large, round face and excessive fat around the torso. Too much aldosterone leads to a condition called hyperaldosteronism, which can cause high blood pressure and low potassium levels.
The Merck Manuals Online Medical Library explains that adrenal adenomas--noncancerous tumors--are common and affect half of all people by the time they reach 70.
