From the Guidelines
The IGRA test is not the same as the Quantiferon test, although Quantiferon is a specific brand of IGRA test. The IGRA test is a general term that refers to a type of test that measures the immune response to Mycobacterium tuberculosis, while Quantiferon is a specific commercial test that uses this technology 1. Other IGRA tests, such as T-SPOT.TB, also exist and work on similar principles but use different methodologies 1.
Key Differences and Similarities
- All IGRA tests, including Quantiferon, detect the immune response to M. tuberculosis rather than the bacterium itself, making them more specific than the traditional tuberculin skin test, especially in people who have received the BCG vaccine 1.
- IGRA tests are preferred over tuberculin skin tests in certain populations, such as immunosuppressed individuals and those with cancer, due to their higher sensitivity and specificity 1.
- Quantiferon-TB Gold and Quantiferon-TB Gold Plus are commercial IGRA tests manufactured by Qiagen that detect tuberculosis infection by measuring interferon-gamma release from T-cells in response to TB antigens 1.
- Healthcare providers should specify which particular IGRA test they are ordering, as laboratory procedures and interpretation may differ slightly between the various commercial IGRA products 1.
Clinical Implications
- IGRA tests, including Quantiferon, are useful for diagnosing M. tuberculosis infection in adults and children, and can be used for surveillance purposes and to identify persons likely to benefit from treatment 1.
- A positive IGRA test result should be followed by an evaluation to rule out active TB, including clinical history, physical examination, and chest X-radiograph or thoracic CT scan 1.
- The choice of IGRA test may depend on the specific clinical context and the availability of testing facilities 1.
Test Characteristics
- IGRA tests require only a single patient visit for specimen collection, with results typically available within 24 hours 1.
- The tests measure the immune response to M. tuberculosis antigens, rather than the presence of the bacterium itself, making them more specific than traditional tests 1.
From the Research
IGRA Test and Quantiferon Comparison
The Interferon-Gamma Release Assay (IGRA) test and the Quantiferon test are related but not exactly the same.
- The IGRA test is a type of blood test that measures the immune system's response to tuberculosis (TB) bacteria by detecting the release of interferon-gamma [ 2 ].
- The Quantiferon test is a specific type of IGRA test that uses a blood sample to detect the presence of TB infection [ 3 ].
Key Differences and Similarities
Some key points to consider:
- Both IGRA and Quantiferon tests are used to diagnose latent TB infection [ 4 ].
- The Quantiferon test is a specific type of IGRA test that has been widely used and studied [ 5 ].
- Other types of IGRA tests, such as the T-SPOT.TB test, are also available and may have similar or different performance characteristics compared to the Quantiferon test [ 6 ].
Clinical Use and Interpretation
In clinical practice, the choice of IGRA test may depend on various factors, including: