Quantiferon Gold TB Test in Delhi

TB Quantiferon Gold Test

The TB Quantiferon Gold (QFT) test is a modern blood test used to detect latent or active tuberculosis (TB) infection. It is an Interferon-Gamma Release Assay (IGRA), meaning it measures the immune system’s response to TB bacteria (Mycobacterium tuberculosis) by detecting the release of interferon-gamma when blood is exposed to TB-specific antigens. Unlike the Mantoux test, it does not require a follow-up visit to check the result and is not affected by prior BCG vaccination.

Why It Is Done?

Doctors recommend the Quantiferon Gold test to:

Diagnose the latent TB infection, especially in high-risk individuals.
Screen people before starting immunosuppressive therapy (like steroids, biologics).
Test healthcare workers or people in close contact with TB patients.
Confirm TB infection in individuals who have received the BCG vaccine.

Symptoms

Persistent cough (lasting more than 2–3 weeks).
Unexplained fever.
Night sweats.
Weight loss.

How to Prepare for the test?

No fasting is required.
Inform your doctor about any immune system disorders or medications that may affect immunity.
Avoid scheduling the test right after a live vaccine (e.g., MMR), as it may alter results.

How It Is Done?

A small sample of blood is drawn from a vein.
The sample is mixed with TB-specific proteins (antigens) in a lab.
The immune cells in the blood will release interferon-gamma if they recognize TB antigens.
The amount of interferon-gamma released is measured to determine the result.

Frequently Asked Questions (FAQs)

1. Is the Quantiferon Gold test better than the Mantoux test?

Yes, it is more specific, has no false positives due to BCG vaccination, and requires only one visit.

2. Can the test differentiate between latent and active TB?

No. It only shows TB infection is present, but further tests like X-ray, sputum are needed to check if it’s active.

3. How long does it take to get results?

Usually the results are out within 24 hours.

4. Can children take this test?

Yes, though some labs may recommend the Mantoux test for children under 5.