Pituitary disorders occur when the pituitary gland produces too many or not enough hormones. Hormones are chemicals that are released into the bloodstream. It is important that the body releases normal amounts of hormones because they send messages to cells throughout the body in order to regulate bodily functions, such as growth, metabolism, and sexual development.
The pituitary gland is a pea-sized gland that is located at the base of the brain. It is just one of many glands involved in the endocrine system. The endocrine system is made up of several glands throughout the body that produce and secrete hormones.
Many experts consider the pituitary gland to be the most important part of the endocrine system because it secretes hormones that regulate the functions of many other endocrine glands. As a result, patients with pituitary disorders may experience a disruption in many different bodily functions.
The pituitary gland secretes several different hormones that are important for normal bodily functions. Growth hormone (GH) regulates bone and tissue growth. It also helps maintain a healthy balance of muscle and fat tissue in the body. Anti-diuretic hormone (ADH) helps control urine production and manages the water balance in the body. Thyroid-stimulating hormone (TSH) signals the thyroid gland to secrete other hormones that regulate the body's metabolism. Luteinizing hormone (LH) regulates testosterone production in males and estrogen production in females. Follicle-stimulating hormone (FSH) signals sperm production in males and egg development and ovulation in females. Adrenocorticotropic hormone (ACTH) stimulates the adrenal glands to produce other hormones, such as cortisol. Prolactin regulates the development of breasts and breast milk in females. Although low levels of prolactin are present in males, there is no known function of prolactin in males.
If the pituitary gland releases too many hormones, disorders, such as acromegaly, Cushing's disease, or hyperprolactinemia, may develop. If the pituitary gland does not release enough hormones, patients develop a condition called hypopituitarism. Most pituitary disorders occur when a noncancerous tumor (abnormal growth) develops on the pituitary gland. A tumor may stimulate the gland to produce too many or not enough hormones.
Treatment of pituitary disorders depends on the type and severity of the disorder. In general, tumors of the pituitary gland need to be surgically removed. Sometimes the entire tumor cannot be removed. In such cases, patients may also need radiation or drug therapy. Even if the tumor is removed, some patients with overactive or underactive pituitary glands may require long-term hormone replacement therapy.
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common types and causes of pituitary disorders
Acromegaly: Acromegaly is a rare hormonal disorder that occurs when the pituitary gland secretes too much growth hormone. As a result, the bones in the hands, feet, and face increase in size. If left untreated, acromegaly can be life threatening. Serious complications may include high blood pressure, heart disease, and spinal cord compression.
Acromegaly is usually caused by a noncancerous tumor of the pituitary gland that secretes too much growth hormone.
Acromegaly may also develop in patients who have tumors in other parts of the body, such as the pancreas, adrenal gland, or lungs. It is possible for these tumors to secrete growth hormone into the bloodstream and cause acromegaly. In rare cases, these tumors may secrete growth hormone-releasing hormone (GH-RH), which signals the pituitary gland to release more growth hormone and causes acromegaly.
This condition usually occurs in middle-aged adults. However, children may also develop acromegaly. When children produce too much growth hormone, the condition is often called gigantism. These children have large bones and are abnormally tall.
Cushing's disease: Cushing's syndrome, or hypercortisolism, is a condition that is characterized by a fatty hump between the shoulders (called a buffalo hump), a rounded face (called a moon face), and stretch marks on the skin.
The condition is caused by long-term exposure to high levels of cortisol, a hormone that reduces inflammation (swelling) in the body. Cushing's disease develops when the pituitary gland releases too much adrenocorticotropic hormone (ACTH), which stimulates the adrenal glands to release cortisol.
Hyperprolactinemia: Hyperprolactinemia occurs when the pituitary gland produces too much prolactin. Hyperprolactinemia leads to decreased levels of sex hormones; testosterone in males and estrogen in females.
Symptoms vary depending on the amount of excess prolactin in the blood. Although the condition is not life threatening, patients may suffer from visual impairments, underdeveloped sex organs, or infertility. Others may experience no symptoms.
The most common cause of hyperolactinemia is a noncancerous tumor on the pituitary gland called a prolactinoma. This tumor produces too much prolactin. However, the cause of these tumors remains unknown.
Some medications, including tranquilizers (such as Stelazine®), gastroesophageal reflux disease (GERD) drugs (such as Reglan®), and high blood pressure drugs (such as Aldmet®), may also lead to hyperprolactinemia. These medications either reduce or block the action of a chemical in the brain called dopamine. This brain chemical normally suppresses the secretion of prolactin. When there are low levels of dopamine in the body, too much prolactin may be released.
Hyperprolactinemia may also develop in patients with underactive thyroid glands (hypothyroidism). Low levels of thyroid hormones have been shown to increase the amount of prolactin in the body.
It is normal for prolactin to increase during pregnancy. After the baby is born, prolactin levels return to normal, except when the baby feeds. During breastfeeding, the suckling action of the baby stimulates the release of prolactin. Increases in this hormone cause the breasts to fill with milk in preparation for the next feed.
It is also normal for prolactin levels to slightly increase as a result of breast stimulation that is unrelated to pregnancy or breastfeeding.
Hypopituitarism: Hypopituitarism is a hormonal disorder that occurs when the pituitary gland does not secrete enough of one or more hormones. Depending on the type and severity of the hormone deficiency, any number of the body's functions may be affected, including growth, blood pressure, and reproduction.
The condition occurs when the pituitary gland becomes injured or damaged. Brain tumors are the most common cause of hypopituitarism. Several other conditions, including head injuries, brain surgery, radiation therapy performed on the head, inflammation in the brain, stroke, brain infections (such as meningitis), tuberculosis, blood loss during childbirth that decreases the blood supply to the brain, genetic mutations, and diseases (e.g. sarcoidosis or histiocytosis), may also lead to hypopituitarism.