Pituitary Gland Tumor: Diagnosis

Approved by the Cancer.Net Editorial Board, 11/2014

ON THIS PAGE: You will find a list of the common tests, procedures, and scans that doctors can use to find out what’s wrong and identify the cause of the problem. To see other pages, use the menu on the side of your screen.

Doctors use many tests to diagnose a tumor and find out if it has spread to another part of the body, called metastasis. Some tests may also determine which treatments may be the most effective. For most tumors, a biopsy is the only way to make a definitive diagnosis. For a pituitary tumor, the biopsy is done as part of surgery to remove the tumor, and a biopsy alone is not usually recommended. The doctor may suggest other tests that will help make a diagnosis. Imaging tests may be used to find out whether the tumor has spread, but very few pituitary tumors ever spread. When they do, they are called pituitary carcinoma instead of the much more common, noncancerous pituitary adenoma. Your doctor may consider these factors when choosing a diagnostic test:

  • Age and medical condition

  • Type of tumor suspected

  • Signs and symptoms

  • Previous test results

In addition to a physical examination, the following tests may be used to diagnose a pituitary gland tumor. This list describes options for diagnosing a pituitary gland tumor, and not all tests listed will be used for every person.

  • Neurological examination. An evaluation of the patient’s central nervous system may include testing a person’s reflexes, motor and sensory skills, balance and coordination, and mental status.

  • Laboratory tests. A blood test may be recommended so the doctor can measure the amounts of certain hormones in the blood. If Cushing's disease, which is described in Signs and Symptoms, is suspected, samples of saliva may be collected as well as one or more 24-hour urine samples. That means all urine produced in a 24-hour period is saved and sent for analysis of cortisol levels. These tests may need to be repeated several times so the doctor can understand how hormones are produced over time, or to confirm that hormone levels are consistently abnormal. Sometimes a person may be given a drug or hormone before the blood measurements are done; this is called provocative testing.

  • Magnetic resonance imaging (MRI). An MRI uses magnetic fields, not x-rays, to produce detailed images of the body. MRI can also be used to measure the tumor’s size. A special dye called a contrast medium is given before the scan to create a clearer picture. This dye can be injected into a patient’s vein or given as a pill to swallow. MRI is better than a computed tomography scan, which is described below, to diagnose most pituitary gland tumors, and it is now the standard method. A traditional MRI of the brain is not sufficient to evaluate the pituitary gland, so an MRI of the pituitary gland tumor is needed.

  • Computed tomography (CT or CAT) scan. A CT scan creates a three-dimensional picture of the inside of the body with an x-ray machine. A computer then combines these images into a detailed, cross-sectional view that shows any abnormalities or tumors. A CT scan can also be used to measure the tumor’s size. Sometimes, a special dye called a contrast medium is given before the scan to provide better detail on the image. This dye can be injected into a patient’s vein or given as a pill to swallow. A CT scan is usually used only for patients who have a pacemaker or an aneurysm clip, which may prevent them from having an MRI, which is described above.

  • Visual field exam. A large pituitary gland tumor may press on the optic nerves, which are located above the pituitary gland. In this test, the patient is asked to find points of light on a screen, using each eye separately. The most common visual field problem caused by a pituitary gland tumor is loss of the ability to see objects along the outside of the person’s field of vision. Because other diseases can also cause vision loss, such as glaucoma, it is important for the doctor to consider all possible causes carefully before coming to a conclusion about the reason for the vision problem.

  • Biopsy. A biopsy is the removal of a small amount of tissue for examination under a microscope. Other tests can suggest that a tumor is present, but only a biopsy can make a definite diagnosis. A pathologist then analyzes the sample(s). A pathologist is a doctor who specializes in interpreting laboratory tests and evaluating cells, tissues, and organs to diagnose disease. A pituitary gland tumor should be checked by the pathologist for production of each of the hormones mentioned in the Overview section, with the exception of lipotropin and melanocyte stimulating hormone, to correctly classify the tumor. As mentioned above, the biopsy is done as part of the surgery to remove the pituitary tumor. In fact, usually the goal is to remove as much tumor as is possible during the biopsy. If there is another medical problem found, then the biopsy is performed in order to be able to come up with the best treatment plan.

  • Lumbar puncture. Lumbar puncture, also called a spinal tap, is a procedure in which a doctor uses a needle to take a sample of cerebrospinal fluid (CSF) to look for tumor cells, blood, or tumor markers. Tumor markers are substances found in higher than normal amounts in the blood, urine, or body tissues of people with certain kinds of tumors. CSF is the fluid that flows around the brain and the spinal cord. Doctors generally give an anesthetic to numb the lower back before the procedure. This test is rarely needed to help diagnose a pituitary tumor. It is usually only useful if the diagnosis of germinoma or sarcoidosis is suspected.

After diagnostic tests are done, your doctor will review all of the results with you. If the diagnosis is a tumor, these results also help the doctor describe the tumor; this is called staging.

The next section in this guide is Stages, and it explains the system doctors use to describe the extent of the disease. Or, use the menu on the side of your screen to choose another section to continue reading this guide.