The Mantoux tuberculin skin test is often used to screen people at high risk for TB. Those who have been previously immunized may have a false-positive test result. The test may be falsely negative in those with sarcoidosis, Hodgkin's lymphoma, malnutrition, and most notably, active tuberculosis. Interferon gamma release assays (IGRAs), on a blood sample, are recommended in those who are positive to the Mantoux test. These are not affected by immunization or most environmental mycobacteria, so they generate fewer false-positive results. However, they are affected by M. szulgai, M. marinum, and M. kansasii. IGRAs may increase sensitivity when used in addition to the skin test, but may be less sensitive than the skin test when used alone. COUNT 5
QSN1 What result might someone who has received a TB vaccination get from the Mantoux test? ANS1 false-positive QSN2 What liquid would you need from a patient to perform IGRAs? ANS2 blood QSN3 In combination with skin tests, are IGRAs associated with an increase or decrease in sensitivity? ANS3 increase QSN4 Which test has fewer false positives: IGRAs or the Mantoux skin test? ANS4 IGRAs QSN5 What does "IGRAs" stand for? ANS5 Interferon gamma release assays