Hypoaldosteronism

Definition

Tumors that occur on one or both of the adrenal glands.

Description

The two small adrenal glands, one located just above each kidney, are among the many endocrine (hormone-secreting) glands in the body. All endocrine glands make and store hormones. Hormones are chemical messages that are sent from an endocrine gland and are received by an organ or a cell to trigger a specific reaction. When the body requires hormone levels to rise, endocrine glands secrete them into the bloodstream. Adrenal gland tumors often cause overproduction of one or a combination of the adrenal hormones.

An adrenal gland has two parts, each of which secretes different hormones. The inner part is called the adrenal medulla, and the outer part is the adrenal cortex.

The adrenal medulla secretes the hormones epinephrine and norepinephrine. These hormones help maintain normal blood pressure. In high-stress situations, they help prepare the body for quick action by increasing heartbeat and breathing rate, increasing the flow of blood to the heart and lungs, and increasing blood pressure.

The adrenal cortex secretes aldosterone and cortisol. They also make small amounts of androgens, which affect the expression of female and male sex characteristics. Aldosterone helps maintain normal salt levels in the blood and the normal functioning of the kidneys. Cortisol (also called hydrocortisone) is the major adrenal hormone.

Cortisol is a steroid, an organic compound that affects metabolism. Many hormones and drugs used to relieve swelling and inflammation are steroids. Cortisol helps maintain blood pressure and is crucial in the breakdown of proteins, carbohydrates, and fats. It also raises blood sugar (glucose) when levels are too low, thus providing needed energy for the body's activities. Cortisol also prevents inflammation and is important for the normal response to stress.

The level of cortisol in the blood is carefully controlled. When the body needs cortisol, a small area of the brain called the hypothalamus releases coricotripoin-releasing hormone (CRH). The pituitary gland, located at the base of the brain, receives the message from the hypothalamus and begins secreting adrenocorticotropic hormone (ACTH). ACTH is received by the cortex of the adrenal glands, which responds by producing cortisol. When the level of cortisol meets the body's need, the pituitary stops producing ACTH, which then stops the adrenal cortex from secreting cortisol.

About 8% of people worldwide develop benign (noncancerous) adrenal tumors. Malignant (cancerous) tumors are very rare, occurring in two out of every one million people worldwide, and this cancer is more common in women than in men.

It is often difficult for a pathologist to distinguish between a benign and a malignant adrenal tumor. Several criteria are used to make a diagnosis, including the size and weight of the tumor, whether hormones are produced, and what hormones are produced. A benign tumor (adenoma) is usually less than 4-6 centimeters (1.57-2.3 inches) in diameter and likely causes changes in the blood level of only one hormone or may cause no changes at all. A malignant tumor is larger and may alter the level of several adrenal hormones. One reliable indicator for a malignant tumor is evidence that the cancer has spread (metastasis).

Types of cancers

Adrenal cortex

A disorder caused by an adrenal cortex tumor can occur alone, but often two or more conditions occur simultaneously. These disorders include

• Cushing's syndrome: a disorder resulting from prolonged exposure to high levels of cortisol. Most cases are the result of a pituitary gland dysfunction that causes excessive secretion of ACTH, but 20-25% are caused by a benign adrenal tumor, of which about 50% are malignant. Symptoms include obesity, moon-shaped face, increased fat in neck region, skin that bruises easily, severe fatigue, weak muscles, and high blood pressure. The common treatment is surgical removal of the affected gland. The outcome for a Cushing's syndrome patient with a benign adrenal adenoma is very good. Surgery usually results in a cure. The outcome is variable for malignant tumors.

• Aldosteronism (also called Conn's disease or hypoaldosteronism): a condition resulting from an abnormally high level of the hormone aldosterone. It is usually caused by an adenoma and rarely is the result of a malignant adrenal tumor. Symptoms include headaches, weakness, fatigue, high blood salt levels, frequent urination, high blood pressure, and an irregular heartbeat. An adenoma is usually removed surgically, although medication that controls the secretion of aldosterone is an effective treatment in many cases.

• Virilization syndrome (also called adrenal virilism or adrenogenital syndrome): a disorder caused by an excessive secretion of androgen hormones, leading to high levels of the male hormone testosterone. Adenomas that cause virilization are rare. When the condition accompanies Cushing's syndrome it may indicate an adrenocortical carcinoma. In males, the symptom is early onset of puberty, whereas in females symptoms include deepening of voice, a masculine build, and abnormal hairiness. The recommended treatment depends on the cause. If the condition is caused by an adenoma, use of medications that surpress ACTH secretion by the pituitary is the preferred treatment.

• Adrenocortical carcinoma: a rare cancer that is often not detected until it has spread to the liver or lung. The symptoms can include that of Cushing's syndrome, aldosteronism, virilization, or a combination of each of these conditions. The preferred treatment depends on the stage of the cancer, but usually involves surgery to remove the tumor, chemotherapy, and radiation therapy. If the cancer is caught at an early stage, the long-term survival can be good. If found at a later stage, about 30% of patients will survive five years after the initial diagnosis.

Adrenal medulla

Only one type of tumor is associated with the adrenal medulla:

• Pheochromocytoma: a tumor that produces and secretes epinephrine and norepinephrine. Excessive secretion of these hormones can cause life-threatening hypertension and an irregular heartbeat. About 90% of these tumors are benign. Five percent of those diagnosed with this tumor have either Von Hippel-Lindau syndrome, type 2 of the multiple endocrine neoplasia syndromes (MEN), Von Recklinghausen's neurofibromatosis, or another inherited disorder. Symptoms include headaches, sweating, and chest pains. Treatment involves medication to control hypertension and the surgical removal of the affected gland. Long-term survival depends on early detection of the tumor and whether the tumor is benign or malignant.

KEY TERMS

Adenoma

A benign tumor.

Inherited disorder

A disease that has a tendency to occur within a family. A disorder may be acquired because of a gene or genes that are passed from parent to child.

Pathologist

A doctor specializing in the identification of diseases by studying cells and tissues under a microscope.