Pituitary Gland Tumor: Diagnosis

Approved by the Cancer.Net Editorial Board, 03/2016

ON THIS PAGE: You will find a list of common tests, procedures, and scans that doctors use to find the cause of a medical problem. To see other pages, use the menu.

Doctors use many tests to find, or diagnose, a tumor. They also do tests to learn if cancer has spread to another part of the body from where it started. If this happens, it is called metastasis. For example, imaging tests can show if the cancer has spread. Imaging tests show pictures of the inside of the body. Doctors may also do tests to learn which treatments could work best.

For most types of tumors, a biopsy is the only sure way for the doctor to know whether an area of the body has a tumor. In a biopsy, the doctor takes a small sample of tissue for testing in a laboratory. If a biopsy is not possible, the doctor may suggest other tests that will help make a diagnosis.

This list describes options for diagnosing this type of tumor, and not all tests listed will be used for every person. Your doctor may consider these factors when choosing a diagnostic test:

  • The type of a tumor suspected

  • Your signs and symptoms

  • Your age and medical condition

  • The results of earlier medical tests

In addition to a physical examination, the following tests may be used to diagnose a pituitary gland tumor. 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.

  • Computed tomography (CT or CAT) scan. A CT scan creates a 3-dimensional picture of the inside of the body using x-rays taken from different angles. 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.

    Other diseases can also cause vision loss. That’s why it’s 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. The sample removed during the biopsy is analyzed by a pathologist. 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 Introduction 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.

  • Lumbar puncture (spinal tap). A lumbar puncture 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.

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. It explains the system doctors use to describe the extent of the disease. Or, use the menu to choose another section to continue reading this guide.