QuantiFERON-TB Gold (Interferon-gamma release assay (IGRA)
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Detects latent or active tuberculosis (TB) infection
₹999₹2400
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🧪 What is QuantiFERON-TB Gold (IGRA)?
The QuantiFERON-TB Gold test is a blood test that detects latent or active tuberculosis (TB) infection by measuring the release of interferon-gamma (IFN-γ) from T-cells in response to specific Mycobacterium tuberculosis antigens.
It is an alternative to the traditional tuberculin skin test (TST) and is more specific for TB infection.
❓ Why is the Test Done?
To:
- Detect latent TB infection in individuals without active disease
- Support diagnosis of active TB, especially in cases where sputum is negative or unavailable
- Screen high-risk populations (healthcare workers, immunocompromised patients, contacts of TB cases)
- Guide decisions on TB preventive therapy
🔬 How the Test Works
- Blood is drawn and incubated with TB-specific antigens (ESAT-6, CFP-10, TB7.7)
- If the patient’s immune cells recognize TB antigens, they release interferon-gamma
- The amount of IFN-γ released is measured by ELISA
📊 Interpretation of Results
Result | Meaning |
|---|---|
Positive | Evidence of TB infection (latent or active) |
Negative | No evidence of TB infection |
Indeterminate | Test inconclusive; may be due to immunosuppression or technical issues |
📈 Clinical Use
Scenario | Utility |
|---|---|
Latent TB screening | High specificity, especially in BCG-vaccinated individuals |
Active TB diagnosis | Supportive, but not definitive |
Immunocompromised patients | Useful, but may yield indeterminate results |
🧠 Associated Conditions
Condition | Details |
|---|---|
Latent tuberculosis infection | Immune sensitization without clinical disease |
Active tuberculosis disease | Pulmonary or extrapulmonary TB |
🔄 Related / Follow-Up Tests
- Chest X-ray – to detect active pulmonary disease
- Sputum smear and culture for Mycobacterium tuberculosis
- Tuberculin Skin Test (TST) – alternative screening method
- Molecular tests (GeneXpert) – rapid diagnosis of active TB
✅ Fasting Required?
Test | Fasting Required |
|---|---|
QuantiFERON-TB Gold (IGRA) | ❌ No |
📝 Summary Table
Parameter | Details |
|---|---|
What | Blood test detecting IFN-γ release after TB antigen exposure |
Why | Detect latent or active TB infection |
Interpretation | Positive, negative, or indeterminate |
Associated Conditions | Latent TB, active TB |
Follow-up Tests | Chest X-ray, sputum culture, molecular TB tests |
Fasting Required | ❌ No |
How our test process works!
