The pituitary gland weighs about 0.5 to 1 gram and is divided into an anterior and a posterior lobe. It is located at the base of the brain and is connected to the brain by a thin stalk. Magnetic resonance imaging (MRI) is the best method for visualization of pituitary gland and its associated disorders, such as pituitary tumors. There are many conditions that involve the pituitary: pituitary tumors; pituitary cysts; infections and inflammatory conditions and non-pituitary tumors. Pituitary tumors are responsible for a majority of hormone abnormalities involving the pituitary glands.
Description of Pituitary Tumors
Pituitary Tumors (adenomas)
Pituitary tumors are common. In autopsy studies of patients who did not have known pituitary disease, up to 20% had small tumors in their pituitary glands. There are no known environmental causes for pituitary tumors. Very rarely they can run in families and may be associated with some other diseases such as high blood calcium level and certain types of abdominal tumors. Over 99% of pituitary tumors are benign (not a cancer). Although the tumors are benign, they can cause problems because of their size, because they cause the normal pituitary gland to become underactive (hypopituitarism) or because they cause excessive hormone production.
By far the most common type of tumor of the pituitary gland tumors (about half of all cases) are the "non-functioning" tumors. These pituitary tumors, which are not associated with any clinical manifestations secondary to excess hormone secretion. They may cause problems due to their size such as headaches and visual problems or they can press on the pituitary gland, causing it to stop producing the required amount of one or more of the pituitary hormones, leading to hormone deficiency.
Hyperprolactinemia (elevated prolactin)
A prolactinoma is a prolactin-producing tumor of the pituitary gland. These tumors come in various sizes, but the vast majority are less than 10mm (½ inch) in diameter. These are called microprolactinomas. The larger pituitary tumors are called macroprolactinomas. Prolactinomas can occur in both men and women. They may cause discharge from breasts (galactorrhea), irregular periods (oligomenorrhea) or loss of normal menstrual function (amenorrhea) in females and impotence in men. In addition, large prolactinomas may cause symptoms due to their size or other pituitary hormone deficiency that is seen in nonfunctional tumors.
Most patients with prolactinoma do not require surgery, as most prolactinoma tumors (even very large ones) shrink in size following treatment with medication.
Galactorrhea (abnormal breast discharge)
Sometimes a woman's breast makes milk even though she is not breast feeding a baby. This is called galactorrhea. The milk may come from one or both breasts. It may leak with no stimulation or it may leak only when the breasts are touched. Galactorrhea can be caused by medicines, Herbs, street drugs, hormonal imbalance, pituitary tumors, pregnancy, tight clothing that irritates breast and stimulation of the breast during sexual activity. Sometimes the cause can't be found.
Cushing's disease describes the condition resulting from too much exposure to steroid hormones. The commonest cause of it is the usage of synthetic steroids. The excess production of ACTH by pituitary gland tumors is the next most common cause. This in turn stimulates the adrenal glands to produce excess steroid hormone called cortisol. Cushing's disease can also be caused by a small growth in one, or both, of the adrenal glands or less likely tumors in the lungs or pancreas. The disease is more common in women and mostly seen in middle-age groups, although it can be seen in any age.
Patients often complain of progressive weight gain, depression, muscle weakness, easy skin bruising, impotence (in men) and irregular periods (in females). The treatment is usually surgery, which needs to be done by an experienced neurosurgeon. Radiotherapy may be used in some patients that are not cured by surgery. Medical therapy has only a limited role in the management of this disease.
Acromegaly (growth hormone excess)
Acromegaly is rare disease associated with too much growth hormone (GH). It is mostly caused by pituitary gland tumors. It is usually seen in middle age patients. If the disease develops before a person has stopped growing, then it causes gigantism since two much growth hormone promotes growth of bones in the body. Enlargement of the hands, feet and face and excessive sweating are the most common features of excessive growth hormone production. Some of other clinical features include large headaches, irregular periods (in women), impotence (in men) and vision disturbances. The facial changes in patients with acromegaly occurs very slowly. For this reason the patient or family may not become aware of them. The disease may cause enlarged heart, tingling or pain in extremities (peripheral neuropathy), restless sleep with sleepiness during the day (sleep apnea). It may also be associated with increased tendency for colon cancer. The primary treatment is usually surgery followed by radiotherapy or medications depending on patient’s clinical status.
Growth Hormone deficiency
Growth Hormone (GH) is a protein made in the pituitary gland and passed from there into the blood stream. GH has effects on virtually all the organs of the body, but its primary use during childhood is making children grow. GH deficiency is usually caused by damage to the pituitary gland or the part of the brain, which controls this gland (the hypothalamus). The damage may be due to tumors or to the effects of treatment for the tumors (surgery or radiotherapy). Some of the associated clinical features in adults patients with growth hormone deficiency include increase in fatty tissue, decrease in muscle mass, decrease in strength and stamina, decrease in bone density, excessive tiredness and feelings of social isolation (reduction in quality of life). Some of studies suggest that treatment with GH may have some beneficial effect on lipid profile (cholesterol) and heart function.
Hypopituitarism and Panhypopituitarism
The pituitary gland produces a number of hormones or chemicals, which are released into the blood to control other glands in the body. If the pituitary is not producing one or more of these hormones, or not producing enough, then this condition is known as hypopituitarism. If all the hormones produced by the pituitary are affected this condition is known as panhypopituitarism.
Hypopituitarism is most often caused by benign (not cancerous) tumors of the pituitary gland, or of the brain in the region of the hypothalamus. Pituitary underactivity may be caused by the direct pressure of the tumor mass on the normal pituitary or by the effects of surgery or radiotherapy used to treat the pituitary tumors. Less frequently, hypopituitarism can be caused by infections (such as meningitis) in or around the brain or by severe blood loss, by head injury, or by other rare diseases.
Some of the clinical features that may be associated with hypopituitarism include excessive tiredness and decreased energy, irregular periods (oligomenorrhea) or loss of normal menstrual function (amenorrhea), impotence (in men), infertility, increased sensitivity to cold, constipation, dry skin, low blood pressure and dizziness on standing (postural hypotension). Each of the symptoms described above occur in response to the loss of one or more of the hormones produced by the pituitary.
Special instructions when coming to see doctors for parathyroid disorders and pituitary tumors:
Instructions for your appointment
- Bring all records including labs, CT scan, MRIs and other imaging studies.
Tests for pituitary disorders
The following tests for pituitary tumors and disorders may be ordered by your physician:
- Insulin Tolerance Test
- Dexamethasone Suppression
- GHRH Stimulation Test/Argenine Stimulation Test
- Growth Hormone Suppression Test/ Oral Glucose Tolerance Test
MRI of the pituitary gland
Special treatment procedures
The following procedures are done in collaboration with departments of Radiation Oncology and Neurosurgery:
- Gamma knife
- Traditional radiation treatment including IMRT
- Surgical treatment for pituitary tumors