Pituitary tumors are usually found by different test when a person experience the symptoms caused by it.
Pituitary tumors are usually found by different test when a person experience the symptoms caused by it. But the tumors which do not cause any symptoms are found when doing medical tests done for other health problems. Several tests are needed to be sure of the diagnosis and find out what kind of pituitary tumor it is. These may include:
Medical history and physical examination:
A complete medical history to check for risk factors and to know more about your symptoms can be done at the initial stage. Your family history of tumors or other problems will be analyzed to see if you might have an inherited genetic syndrome, such as multiple endocrine neoplasia, type I (MEN1).
Vision problem or nervous system problems that could be caused by a tumor can be looked for possible signs of a pituitary tumor. As pituitary tumors can damage nerves leading to the eyes, a complete eye test should be done which include field of vision or visual fields. Pituitary tumors can press on part of the optic nerves often leading to the loss of peripheral vision. In this condition you can not see things off to the side without actually looking right at them.
You will be then referred to an endocrinologist or a neurosurgeon, who might order other tests.
Blood and urine tests of hormone levels:
Hormone levels in your blood and/or urine will be measured if a hormone-producing pituitary tumor is suspected.
Growth hormone-secreting adenoma:
As the signs and symptoms are often very distinctive in this adenoma, a physical test can give you a hint of this. The levels of growth hormone and insulin should be checked then. Growth factor-1 (IGF-1) in your blood samples are taken in the morning after an overnight fast.
When growth hormone levels are high, they cause the liver to make more IGF-1. IGF-1 level does not change much during the day, while the level of growth hormone can go up and down. Therefore testing the IGF-1 level can be more helpful than checking the level of growth hormone. If both levels are very high, a pituitary tumor is diagnosed. If the levels are slightly increased, a glucose suppression test is often done to be sure. In this test you will be asked to drink a sugary liquid and the levels of growth hormone and blood sugar will be measured at certain intervals. A drop in growth hormone levels should occur in response to suddenly taking in so much sugar for a normal person. If the growth hormone levels stay high, a pituitary adenoma is likely the cause.
Corticotroph, Corticotropin or ACTH-secreting adenoma:
The levels of cortisol in your saliva late at night is tested to see if they stay elevated as they normally drop at night. Measuring levels of cortisol and ACTH in blood samples taken at different times of the day is another way to make the diagnosis. Your daily production of cortisol and other steroid hormones can be tested by a 24-hour urine test. For this test you will have to collect all of your urine over a 24-hour period.
Blood or urine cortisol levels can be checked after taking a dose of a powerful cortisone-like drug called dexamethasone. Often more than 1 of these tests is needed to help distinguish ACTH-secreting pituitary tumors from other diseases, such as adrenal gland tumors, that can cause similar symptoms.
Prolactin-secreting adenoma or prolactinoma:
Blood prolactin levels can be measured to check for a prolactinoma.
Luteinizing hormone (LH) and follicle-stimulating hormone (FSH) blood levels can be checked for the diagnosis of gonadotropin-secreting tumor. Levels of related hormones, such as estrogen, progesterone, and testosterone, are also checked most often.
Blood levels of thyrotropin (TSH
) and thyroid hormones can be measured to diagnose a thyrotropin-secreting adenoma.
Blood levels of pituitary hormones may actually be low because the adenoma crowds out the cells that normally make these hormones.
Testing for diabetes insipidus:
Tests that measure the amount of urine made over a 24-hour period, sodium and glucose levels in the blood, and osmolality (total salt concentration) of the blood and urine can be done for the diagnosis of diabetes insipidus
A water deprivation study may also be done. In this test, you are not allowed to drink fluids for several hours. The test is often done overnight. You will continue to make urine even though you are not taking in any fluid if your body is not making enough vasopressin. You may also be given an injection of vasopressin to see if this corrects the problem.
Computed tomography (CT) scan:
X-rays are used to create detailed cross-sectional images of part of your body. CT scans can find a pituitary adenoma if it is large enough. MRI scans are used much more often to look at the brain and pituitary gland.
Magnetic resonance imaging (MRI) scan:
Radio waves and strong magnets are used in MRI to create detailed pictures of the brain and spinal cord. These are considered to be the best way to find pituitary tumors of all types. They can show macroadenomas of the pituitary gland, as well as most microadenomas. But MRI might not detect microadenomas that are smaller than 3 mm (about 1/8 inch) across.
MRI images are usually more detailed than those from CT scans.