Which statement best describes the Quantiferon-TB (QFT) blood test?

Which statement best describes the Quantiferon-TB (QFT) blood test?

• A. A test that measures TB antibodies
• B. An alternative to the Mantoux test that indicates TB infection and requires a single visit
• C. A test that confirms active TB infection
• D. A test that screens for TB by chest imaging

Answer: (B)

Quantiferon-TB is an interferon-gamma release assay that uses a blood sample to detect TB infection by measuring T-cell release of interferon-gamma in response to TB-specific antigens. This makes it an alternative to the tuberculin skin test, with the practical advantage that only one visit is needed for a blood draw and processing, unlike the Mantoux test that requires a second visit to read the result. A positive result indicates TB infection, which could be latent or active; it does not by itself confirm active disease. It does not measure TB antibodies and it is not a chest-imaging screening test.

Quantiferon-TB is an interferon-gamma release assay that uses a blood sample to detect TB infection by measuring T-cell release of interferon-gamma in response to TB-specific antigens. This makes it an alternative to the tuberculin skin test, with the practical advantage that only one visit is needed for a blood draw and processing, unlike the Mantoux test that requires a second visit to read the result. A positive result indicates TB infection, which could be latent or active; it does not by itself confirm active disease. It does not measure TB antibodies and it is not a chest-imaging screening test.