Renal scan

  • Definition

    A renal scan is a nuclear medicine exam in which a small amount of radioactive material (radioisotope) is used to measure the function of the kidneys.

    Alternative Names

    Renogram; Kidney scan

    How the test is performed

    The specific type of scan may vary, depending on the patient's specific needs. This article provides a general overview.

    A renal scan is similar to a renal perfusion scintiscan. It may be done along with that test.

    You will be asked to lie on the scanner table. The health care provider will place a tourniquet or blood pressure cuff on your upper arm, which creates pressure and enlarges your arm veins. The inner elbow is scrubbed with numbing medicine (antiseptic) and a small amount of radioisotope is injected into a vein. The specific radioisotope used may vary, depending on the kidney function that is being studied.

    The pressure on the upper arm is released, which allows the radioactive material to travel through the bloodstream. The kidneys are scanned a short time later. Several images are taken, each lasting 1 or 2 seconds. The total scan time takes about 30 minutes to 1 hour.

    A computer analyzes the images and provides detailed information about particular kidney functions (such as how much blood the kidney filters over time).

    After the scan, no recovery time is required. You may be asked to drink plenty of fluids and urinate frequently to help remove the radioactive material from the body.

    How to prepare for the test

    Tell your health care provider if you take any nonsteroidal anti-inflammatory drugs (NSAIDs) or blood pressure medications, as they might interfere with the exam.

    You may be asked to drink additional fluids before the scan.

    You must sign a consent form.

    You will be asked to wear a hospital gown. Remove jewelry, dentures, and metallic objects before the scan.

    How the test will feel

    There is a sharp prick when the isotope is injected into the vein. You will not feel the isotope. You should not feel the scan, although the table may be hard or cold. You will need to lie still during the scan.

    Why the test is performed

    A renal scan reveals the size, position, shape, and function of the kidneys. It is particularly useful when a person is sensitive or allergic to the contrast (dye) material used in an IVP or other x-rays, or when they have reduced kidney function.

    A renal scan is commonly performed after a kidney transplant to check kidney function and to look for signs of transplant rejection.

    It may also be done on those with high blood pressure to check differential kidney function.