A patient seated in the chair before a blood draw
In person

Tuberculosis Blood Test (QuantiFERON)

A TB blood test of your immune response, with no return visit.

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  • 2,000+ lab locations. Find one near you
  • Nothing due at the lab. FSA / HSA accepted
  • Ordered by a licensed clinician

At a glance

Collection
Blood draw
Four small tubes, one visit.
Preparation
None
Nothing to do ahead of time. Water is fine.
Results
2 to 4 days
Typical turnaround after your visit.
Where
2,000+ lab locations
Nationwide, with nothing due at the lab.

About this test

QuantiFERON is a blood test that measures your immune response to proteins from the bacteria that cause tuberculosis (TB). It uses four small tubes drawn in one visit, with no return visit to read it. A positive result needs more evaluation, and a negative result does not exclude TB in all cases.

For adults 18 and older. Test availability varies by lab location.

Who should take this test?

For adults who need a TB test for school, work, or a volunteer program, or whose provider suggested one. If you have a lasting cough, fever, night sweats, or weight loss, see a provider.

Ask about this test

Not sure this is the right test?

AI-generated. For information only, not medical advice. Call 911 for an emergency.

What does this test measure?

Your result shows whether your blood released an immune signal in response to TB proteins, which a healthcare provider reads with your history and other evaluations.

QuantiFERON-TB Gold Plus (interferon-gamma release assay)
This blood test mixes your blood with proteins from the bacteria that cause tuberculosis and measures whether your immune cells respond. A positive result suggests TB infection but cannot tell latent infection from active disease, which takes more evaluation. Some results are indeterminate, and a provider decides on next steps.
Why it’s measured: A TB blood test that measures the immune response to TB proteins.

How it works

  1. Step 1

    Check your location

    This test uses special tubes that need handling soon after the draw, so availability and collection days can vary by lab location. Nothing to do ahead of time.

  2. Step 2

    Four small tubes

    At the lab, a small amount of blood goes into each of four special tubes during one draw. The lab then handles them as the test requires.

  3. Step 3

    No return visit

    Unlike a TB skin test, there is no second visit to have the result read. The sample goes to the lab for testing.

Find a lab near you

Choose from 2,000+ lab locations nationwide. Your order works at any of them.

What your results tell you

The result is reported as positive or negative, based on the immune signal your blood releases to TB proteins. Some results may be indeterminate.

  • Your number next to the lab’s reference range
  • Explained in plain language
  • A licensed clinician reviews your order and, if appropriate, orders the test.
  • A lab report you can download and share

A positive result needs more evaluation, such as an exam and a chest X-ray, so a healthcare provider can tell latent infection from active TB.

QuantiFERON or T-SPOT?

Both are TB blood tests. They use different lab methods.

QuantiFERON

Measures a signal your blood releases in response to TB proteins.

How it works
Measures interferon gamma released in response to TB proteins
Sample
Four small tubes in one draw
Lab handling
Tubes are kept warm (incubated) before testing

Clinical-grade testing, from the comfort of home.

From the lab to your report, every step of our process meets the gold standard in medical testing.

  • CLIA-certified labs

    Every lab we partner with is certified under the Clinical Laboratory Improvement Amendments, meeting both state and federal standards with regular independent inspections.

  • We protect your health data

    We protect your health data with encryption and do not sell it. Some results must be reported to public health authorities by law. See our Privacy Notice.

  • Rigorous quality assurance

    All partner labs run regular internal quality checks, participate in proficiency testing, and comply with federal and state lab regulations.

  • Clinician-reviewed reports

    Results are reviewed by an independent, licensed clinician.

Questions

Common questions.

Anything else, our care team answers by phone, text, or email.

The four tubes work together. Two contain TB proteins, one has none and serves as a baseline, and one checks that your immune cells can respond at all. Comparing them shows whether your blood reacted to the TB proteins in particular.

The tubes need special handling, so availability and collection days can vary by lab location.

A positive result means your blood responded to TB proteins, which suggests TB infection. The lab notes that more testing is needed to tell latent TB infection, which causes no symptoms, from TB disease. A healthcare provider uses an exam, a chest X-⁠ray, and your history to tell them apart and plan next steps.

Not in all cases. This is an indirect test, meant to be read with your history, an exam, and other evaluations, so a negative result does not exclude TB for everyone. If you have a lasting cough, fever, night sweats, or weight loss, see a healthcare provider rather than relying on this test.

A skin test needs a return visit to read it, while this blood test needs one visit. The lab also notes that a past BCG vaccine, which is given in some countries, does not cause a false positive on this blood test, as it can on a skin test. If your program names a specific TB test, check its requirements.

Some positive results are reported to public health authorities as required by state law. Talk with a healthcare provider about any positive result.