QuantiFERON-TB Gold is the most accurate test for detecting latent tuberculosis quickly and accurately

Has your doctor recommended a QuantiFERON-TB Gold test?
If you're wondering what this test is, why it's needed, and how accurate it is, you're in the right place.In this Dalili Medical article, we’ll walk you through everything you need to know about this modern blood test used to detect latent tuberculosis infection (LTBI) with high precision.
You'll learn how the test works, when it's recommended, and how to interpret the results.

✅ What is the QuantiFERON-TB Gold Test?

The QuantiFERON-TB Gold test (QFT-G) is a blood test used to detect latent tuberculosis infection (LTBI)—an infection that shows no clear symptoms and has not yet developed into active TB disease.

This test is considered a more accurate and advanced alternative to the traditional Mantoux tuberculin skin test (TST), as it is not affected by prior BCG vaccination.

???? Why is the QuantiFERON-TB Gold test requested?

Your doctor may recommend the QuantiFERON-TB Gold test in the following situations:

When latent TB infection is suspected, even without symptoms.
Before starting immunosuppressive treatments, such as chemotherapy or biologics.
If you’ve had close contact with someone with active TB.
As a routine screening for individuals from high TB prevalence areas.
For people working in healthcare settings, prisons, or refugee centers.

???? How is the QuantiFERON-TB Gold test performed?

This test is simple and straightforward:

A blood sample is drawn from a vein (usually 3 to 4 tubes).
The sample is sent to a lab, where T-cells are exposed to TB-specific proteins (from Mycobacterium tuberculosis).
The lab then measures the release of interferon-gamma (IFN-γ), a substance produced by these immune cells.

Results are typically available within 24 to 48 hours.

???? QuantiFERON-TB Gold vs. Mantoux Skin Test

Criteria	QuantiFERON-TB Gold	Mantoux Skin Test (TST)
Sample type	Blood	Skin injection
Result time	1–2 days	48–72 hours
Affected by BCG vaccine	❌ No	✅ Yes — may give false positives
Clinic visits required	One	Two
Accuracy	Higher	Lower

✅ Advantages of the QuantiFERON-TB Gold Test

High accuracy in detecting TB infection.
Not affected by previous BCG vaccination.
Quick results with no need for follow-up visits.
No skin reaction or swelling.
Less interference from non-TB bacterial infections.

❌ Are there any disadvantages?

Despite its high accuracy, the test has a few limitations:

Cannot distinguish between latent and active TB — further tests are needed.
Less accurate in people with severely weakened immune systems (e.g., HIV or cancer patients).
More expensive than the traditional skin test.

???? How to interpret QuantiFERON-TB Gold test results

✅ Negative result:

No evidence of TB infection.
The person is likely not infected.

❗ Positive result:

The immune system has responded to TB proteins, indicating previous exposure.
Further tests, such as a chest X-ray, are needed to determine if TB is latent or active.

⚠️ Indeterminate result:

The test couldn’t provide a clear answer.
Often caused by a weak immune response or sample issues.
The test may need to be repeated.

???? What’s the difference between latent and active TB?

Latent TB:

No symptoms.
Not contagious.
The person often doesn’t know they’re infected.
Can progress to active TB if not treated.

Active TB:

Causes symptoms like persistent cough, fever, and weight loss.
Highly contagious.
Requires immediate medical treatment.

QuantiFERON-TB Gold helps detect latent TB before it becomes active and dangerous.

❓ Frequently Asked Questions

Is this test 100% reliable?

No test is 100% accurate, but QuantiFERON-TB Gold is one of the most sensitive and specific tests for detecting latent TB, especially when used with chest X-ray and clinical history.

Do I need to fast before the test?

No, fasting is not required. The test can be done at any time of day.

Can children take this test?

Yes, it’s suitable for children over 5 years old, although younger children are often tested with the skin test instead.

Will this test be affected if I had the BCG vaccine?

No, and this is one of the major benefits of this test—it is not affected by prior BCG vaccination.

???? Medical Tip:

If your QuantiFERON-TB Gold test result is positive, don’t ignore it—even if you feel fine. Latent TB can be treated before it turns into active disease, so make sure to follow up with your doctor for proper evaluation and management.

✍️ Summary

The QuantiFERON-TB Gold test is a modern and highly effective method to detect latent tuberculosis infection, especially in individuals who may not show symptoms.
It’s more accurate than the traditional skin test and unaffected by prior BCG vaccination. If you work in healthcare or have been exposed to TB, this test could help identify a silent infection before it becomes serious.