TB Gold QuantiFERON
- Sample Type
- Whole Blood
- Fasting
- No
- Unit
- IU/mL
Function
The QuantiFERON-TB Gold (QFT) is an Interferon-Gamma Release Assay (IGRA). It measures the cell-mediated immune response to specific proteins (ESAT-6, CFP-10) that are found in Mycobacterium tuberculosis but are absent from the BCG vaccine and most non-tuberculous mycobacteria.
Why it is Ordered
QFT is used for the detection of Mycobacterium tuberculosis infection, encompassing both latent TB infection (LTBI) and active tuberculosis disease. It is preferred over the Tuberculin Skin Test (TST) for individuals who have received the BCG vaccine or those unlikely to return for a skin test reading.
Associated Conditions
- Latent TB: The patient is infected but asymptomatic and not contagious.
- Active TB: The patient has symptomatic disease (pulmonary or extrapulmonary).
- Screening: Often required for healthcare workers, individuals starting immunosuppressive therapy (like TNF-alpha inhibitors), or immigrants from high-prevalence areas.
Check Your Result
Check Your Result
Enter your lab result to see where you stand compared to the standard reference range.
Why Context Matters
Results can be 'Indeterminate' if the patient's immune system is severely suppressed (low mitogen response) or if the blood samples were handled incorrectly (delays in incubation). Recent viral infections or systemic inflammation can also cause transient fluctuations in interferon levels. A second opinion or re-test is vital if the clinical picture does not match the 'Indeterminate' or borderline 'Positive' result.
Lab ranges are statistical averages, not biological laws. "Normal" for a 20-year-old male isn't normal for a 60-year-old female.
Related Indicators
Medically Reviewed by Dr. Binoy Babu, MBBS
Board Certified Doctor • 10+ Years Clinical Experience
Dr. Babu is a practicing physician dedicated to empowering patients with clear, actionable medical information. He founded 2opi to bridge the gap between complex lab reports and patient understanding, ensuring everyone has access to a reliable second opinion.
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