|  | Conditions Treatments | Medical Conditions

TB Test Guidelines

Tuberculosis is a bacterial disease caused by Mycobacterium tuberculosis. TB usually attacks your lungs, but the bacterium can also spread to your kidney, spine and the brain. If TB is left untreated, it can be fatal. There are two tests used to indicate whether TB is present in your body: a skin test or a blood test. However, these two tests do not show if the bacterial infection has progressed into TB disease.

  1. TB Skin Test

    • The TB skin test, also known as the Mantoux tuberculin skin test, is the most commonly used test. A small amount of liquid, called tuberculin, is injected into the skin on the lower part of your arm. You will need to return to the health care facility within 48 to 72 hours to see if there is a reaction to the tuberculin. A health professional will look for to see whether the skin is raised and discolored. Your arm cannot be examined before 48 hours, as there may be swelling from the injection and discoloration may not appear. If you wait longer than 72 hours, the effects of tuberculin reacting to the tuberculosis bacterium will not be visible.

    TB Blood Test

    • Two examples of TB blood tests are the QuantiFERON®-TB Gold Test (QFT-G) and the T-SPOT®. Unlike the skin test, both blood tests require only one visit. Blood is drawn and run through interferon-gamma release assays (IGRAs). Interferon-gamma release assays measure your immune system's response to the bacterium. However, interferon-gamma release assays are relatively new, and your health care provider may not have them.

    Diagnosis of Disease

    • If the test results come back positive, you will need additional tests to determine whether the bacterial infection has progressed into tuberculosis. The diagnosis includes a medical history, physical examination, chest radiography or X-ray, and appropriate bacteriological or histological examinations.

Medical Conditions - Related Articles