Pituitary Disorders Program
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What is the pituitary gland?
The pituitary gland, located at the base of the brain, is a small organ about the size of an acorn. It is surrounded by a bony saddle-like structure above the sinuses at the back of the nose, called the sella turcica. The pituitary gland is sometimes referred to as the "master gland" because it releases substances, which control the basic functions of growth, metabolism, and reproduction.
The pituitary gland is divided into two parts called lobes. These are referred to as the anterior and posterior lobes. Each lobe releases special substances, or hormones, which control basic activities within the body. The specific hormones and their activities are shown below.
The pituitary gland is responsible for regulating many body tissues. Breast function in females, steroid production by adrenal glands, thyroid function, bone growth and health, sexual function in men and women, fluid and electrolyte and water balance, and contraction of the uterus during childbirth are just some of the functions that it regulates. There is a complex balance of feedback loops between the various body organs and the pituitary that enables the body to function optimally.
What is a pituitary tumor?
Pituitary tumors can grow inside or on the surface of your pituitary gland. Because the pituitary gland is located just below the optic (vision) nerves, pituitary tumors can cause vision problems, including partial loss of vision and even blindness.
View our infographic and learn more about causes, detection and treatment of pituitary tumors.
What are the types of pituitary tumors?
The cause of pituitary tumors is unknown. A small number of these tumors seem to be hereditary. They can occur at any age but are more likely to appear in older adults. The symptoms of pituitary tumors are related to the pressure the tumor exerts on the rest of the gland and nearby structures; this pressure affects the amount of hormones your gland produces.
If the tumor is producing hormones (known as a functioning tumor), the type of hormone it is producing will determine your symptoms.
- Adrenocorticotropic hormone - secreting tumors stimulate your adrenal glands to make cortisol and may result in Cushing’s syndrome in which fat accumulates around your midsection and upper back, your face gets rounder, you may develop a hump on your upper back, you can experience high blood pressure and blood sugar, your muscles may weaken, your skin may thin and bruise more easily and you may become more anxious, depressed or irritable.
- Growth hormone - secreting tumors may cause acromegaly which may coarsen your facial features, enlarge your hands and feet, cause excess sweating, cause high blood sugar, create heart problems and joint pains and increase the growth of body hair.
- Prolactin - secreting tumors (prolactinoma) can cause a decrease in the levels of sex hormones. Women may experience irregular menstrual periods or none at all and a milky discharge from their breasts. Men may experience erectile dysfunction, infertility and loss of sex drive.
- Thyroid - stimulating hormone-secreting tumors produce too much thyroxine, which may accelerate your body’s metabolism and cause sudden weight loss, a rapid or irregular heartbeat, nervousness and irritability, feeling too hot and frequent bowel movements.
How does the pituitary gland affect the body?
There is a delicate cycle of secretion and regulation of these functions that varies by time of day and the degree to which a person is physically and psychologically stressed. Each of these hormones can be tested using a variety of different studies. They can be tested by measuring the individual hormone levels in the blood, but they can also be tested by stimulation or suppression tests, which tell the doctors how well the body's balance and regulation of these hormones is working. We may also refer you to an endocrinologist for more testing.
| Anterior Lobe | Function |
|---|---|
| Thyroid Stimulating Hormone (TSH) | Causes the thyroid gland to grow and release thyroid hormones (called T4 and T3). |
| Adrenocorticotropic Hormone (ACTH) | Causes adrenal gland to release several hormones, particularly cortisol. |
| Growth Hormones (GH) | The main hormone for general body growth as well as regulation of glucose metabolism. |
| Follicle Stimulating Hormone (FSH) | Stimulates ovulation in women and the production of sperm in men. |
| Luteinizing Hormone (LH) | Stimulates ovulation in women and testosterone production in men. |
| Prolactin (PRL) | Elevated during pregnancy produces breast enlargement, lactation, and loos of menstrual cycle. Causes impotence in men. |
| Posterior Lobe | Function |
|---|---|
| Antidiuretic Hormone (ADH) | Controls thirst and the amount fluid reabsorbed into the bloodstream and the amount of urine produced by the kidneys. |
| Oxytocin | Stimulates uterine contractions in women. Its function, if any, in men is unknown. |
Can pituitary tumors cause vision problems?
How are pituitary tumors detected and diagnosed?
What are the signs and symptoms?
A tumor in the pituitary gland causes symptoms by either releasing too much of a hormone or by pressing on the gland causing it to release too little hormone. The symptoms one experiences from the pituitary tumor are often determined by the type of tumor. A tumor that secretes hormones produces symptoms by releasing too much of the hormone. Some tumors cause the gland to stop releasing enough hormones. In this case symptoms arise from lack of hormones. A pituitary tumor may also cause symptoms by growing and pressing on the structures, like the nerves to the eyes, surrounding the pituitary gland.
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