The endocrine system includes a group of glands that produce hormones regulating most bodily functions. The adrenal glands, located just above each kidney, produce hormones that regulate development, growth, physical characteristics and stress responses. An adenoma is a benign, or noncancerous, tumor that forms from the cells of glands. As in any gland of the endocrine system, cells in the adrenal glands can grow out of control and develop into an adenoma.
Adrenal Gland Structure
Each adrenal gland consists of two glands fused together to form one yellowish-orange gland about 2 1/2 by 1 inch long, according to the University of California Department of Surgery. The two separate parts of the adrenal glands produce different types of hormones. The adrenal cortex, which makes up the outer layer of the gland, produces steroid hormones. The inside of the adrenal gland, known as the adrenal medulla, functions within the sympathetic nervous system and produces catecholamine hormones.
Adenoma Classification
Both the cells of the adrenal cortex and the cells of the adrenal medulla can form an adenoma. Some adenomas cause the affected portion of the adrenal gland to produce more hormones than usual. Doctors classify these as functioning tumors. Functioning tumors cause symptoms based on the type of hormone affected. Other adrenal tumors fail to produce any symptoms and are often only discovered by a computed tomography scan or magnetic resonance image performed for other reasons, according to the Dartmouth-Hitchcock Medical Center. Doctors classify this type of adenoma adrenal tumor as a nonfunctioning tumor.
Adrenal Cortex Adenoma
Tumors that form in the adrenal cortex may increase the level of cortisol, a hormone involved in the breakdown of fats, proteins and carbohydrates, the suppression of inflammatory responses and the regulation of blood sugar levels. Adrenal cortex adenomas can also increase the production of aldosterone, a hormone that regulates the electrolyte and water content of blood.
Adrenal Medulla Adenoma
Functioning adrenal medulla adenomas increase the production and secretion of catecholamine hormones. The adrenal medulla produces epinephrine, also known as adrenalin, and norepinephrine, also known as noradrenalin in response to stress. When the body perceives a stressful situation, either physical or emotional, the adrenal medulla increases production of these hormones, which trigger the heart to beat harder and faster, the blood vessels to constrict and an increase in blood flow to the muscles to prepare them for action. A functioning adenoma in the adrenal medulla increases these hormones, resulting in noticeable symptoms.
Symptoms
The symptoms caused by adrenal adenomas vary depending upon the part of the adrenal gland hosting the tumor and the hormones affected. Adenoma tumors in the adrenal cortex can increase the level of cortisol resulting in Cushing's syndrome, a condition characterized by chronic fatigue, weak muscles, high blood pressure, high blood sugar, increased thirst, irritability and depression, according to the National Endocrine and Metabolic Diseases Information Service.
Adenoma in the adrenal medulla that produces too much epinephrine is known as a pheochromocytoma---a rare benign tumor. Pheochromocytoma cause high blood pressure, rapid heartbeat, profound sweating, abdominal pain, sudden headaches, anxiety and weight loss, according to MayoClinic.com.
