QuantiFERON® TB Gold Plus (IGRA)
The QuantiFERON®-TB Gold Plus is an advanced Interferon-Gamma Release Assay (IGRA) blood test. It detects immune sensitization to TB-specific antigens, supporting the clinical assessment of tuberculosis infection without the cross-reactivity seen in traditional skin tests.
Also known as: TB IGRA (Plus) test, Latent TB blood test, QFT-Plus test, Tuberculosis IGRA Plus, Interferon Gamma test.
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Quick Summary of TB Gold Plus Test
- Test Name: QuantiFERON® TB Gold Plus (IGRA)
- Sample Type: Whole Blood (Lithium Heparin: 2 vials of 3ml each)
- Preparation: Fasting is not required.
- No. of Parameters: 5.
- Reporting Time: 50 hours after sample reaches the central lab.
- Results: Qualitative (Positive, Negative, Indeterminate).
Clinical Insight: IGRA vs. Skin Test
The QuantiFERON-TB Gold Plus is an advanced IGRA (Interferon-Gamma Release Assay). Clinicians prefer this blood test over the traditional Mantoux skin test because it does not cross-react with the BCG vaccine, significantly reducing the chances of a false-positive result.
Latent vs. Active TB: A positive IGRA indicates immune sensitization to TB-specific antigens and supports evidence of TB infection. However, it cannot differentiate between Latent TB (dormant, non-contagious) and Active TB (symptomatic, contagious). A final diagnosis always requires correlation with X-rays and symptoms.
Composition of the QuantiFERON TB Gold Plus
| Component (Tube) | What it Represents |
|---|---|
| Tb1 Antigen Tube | TB antigen response (CD4 cell pathway) |
| Tb2 Antigen Tube | TB antigen response (CD4 + CD8 cell pathway) |
| Mitogen Tube | Positive control (validates immune system response) |
| Nil Tube | Baseline interferon-gamma (negative control for correction) |
| Final Result | Positive / Negative / Indeterminate |
Sample Report Preview
View our sample report format of QuantiFERON TB Gold Plus (IGRA) test to see exactly how the algorithmic interpretation and tube responses are presented for your physician’s review.
📄 View Sample Report (PDF)Interpreting the Output
- Positive: Indicates immune sensitization to TB-specific antigens. Clinical correlation is required to assess whether the finding is related to latent TB infection or active TB disease. Clinician correlation is required to check for active disease.
- Negative: Latent TB is unlikely, but it does not completely exclude TB infection (especially in immunocompromised patients).
- Indeterminate: The test’s control tubes did not respond adequately. This can happen due to immune system suppression or pre-analytical factors. Repeat testing and clinician guidance are required.
Diagnostic Limitations
- This is an indirect immune-response test; it is not a standalone diagnostic for active, contagious TB disease.
- Result interpretation heavily depends on immune status; clinician correlation is strictly required.
- The magnitude of interferon-gamma measured cannot be used to stage the disease or track treatment response over time.
Booking Steps
- Send area PIN code to WhatsApp support for slot confirmation.
- Share the name, age, gender, full address, contact details, and preferred collection time for home/office collection.
- A trained and experienced phlebotomist will collect the sample as per the booked slot.
- The report is delivered digitally after processing.
FAQs on QuantiFERON TB Gold Plus Test
How is TB Gold Plus different from the basic TB Gold IGRA test?
Yes. QuantiFERON TB Gold Plus is an advanced IGRA format that includes TB1 and TB2 antigen tubes. TB1 mainly reflects the CD4+ T-cell pathway, while TB2 adds CD8+ T-cell response assessment. This gives a broader immune-response reading than older IGRA formats, but the test still cannot confirm active TB disease by itself.
Is fasting required for this test?
No, fasting is strictly not required for the QuantiFERON TB Gold Plus test. You can provide your sample at any time.
What sample is collected and how much?
Whole blood is collected in two specialized Lithium Heparin vials: 3 ml + 3 ml (total 6 ml of blood).
What is the reporting time for this test?
The reporting time is 50 hours after the sample safely reaches the Central Processing Lab.
Does a positive result confirm active TB disease?
No. A positive result simply indicates immune sensitization to TB antigens (often Latent TB). Comprehensive clinical evaluation (like X-rays and symptom checks) is required to determine active disease status.
What does an indeterminate result mean?
An indeterminate result means the test controls did not respond adequately for a clear interpretation. Your clinician will decide whether repeat testing or alternative methods are needed.
Is home collection available?
Yes. Free home or office collection is scheduled after booking confirmation for the beneficiary’s PIN code and available slot.
Written by: Hema Mehta Sahoo
Medically reviewed by: Dr. M A Khan, MBBS, MD Pathology
Sources:
CDC (IGRAs for TB),
WHO (Tuberculosis),
QIAGEN (QFT-Plus)
Last updated: April 27, 2026