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

T-SPOT TB Test

A TB blood test that measures immune cell response, in one draw.

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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
A standard blood draw at the lab.
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

This blood test measures how your T cells, a type of immune cell, respond to proteins from the bacteria that cause tuberculosis (TB). A provider reads it with your history and other evaluations. 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 asked to get a TB blood test for work or school, or whose provider suggested one. If you have a lasting cough, fever, night sweats, or weight loss, see a provider instead.

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 immune cells reacted to TB proteins, which a healthcare provider reads with your history, an exam, and often a chest X-ray to understand your TB status.

T-SPOT.TB (interferon-gamma release assay)
This blood test counts immune cells that respond to proteins from the bacteria that cause tuberculosis. A positive result suggests TB infection but does not tell latent infection from active disease, so further evaluation is needed. A negative result does not by itself exclude TB.
Why it’s measured: A TB blood test that counts immune cells responding to TB proteins.

How it works

  1. Step 1

    Request your test

    A licensed clinician in your state reviews your request and, if appropriate, signs a lab order for this TB blood test.

  2. Step 2

    Plan your visit

    The sample needs special handling soon after it is drawn, so availability and collection days can vary by lab location. Nothing else to do ahead of time.

  3. Step 3

    One blood draw

    A standard blood draw at the lab. Unlike a TB skin test, there is no second visit to have the result read.

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 how many immune cells respond to TB proteins. Some results may be borderline or invalid.

  • 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 by a healthcare provider, such as an exam and chest X-ray, to tell latent infection from active TB.

QuantiFERON or T-SPOT?

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

T-SPOT

Counts immune cells that respond to TB proteins.

How it works
Counts immune cells that release a signal in response to TB proteins
Sample
A standard blood draw
Lab handling
Short stability, so the sample needs special handling

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.

A positive result means your immune cells responded to TB proteins, which suggests TB infection. On its own, it cannot tell latent infection, which causes no symptoms, apart from active TB disease. A healthcare provider uses more evaluation, such as an exam and a chest X-⁠ray, to tell them apart and plan next steps.

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

A skin test needs a second visit to read the result, while this blood test needs one lab visit. The lab also notes that for TB blood tests, a past BCG vaccine does not cause a false positive, as it can with a skin test. If your program asks for a specific TB test, check its requirements.

Both are blood tests that measure the immune response to TB proteins. T-⁠SPOT counts the immune cells that respond, while QuantiFERON measures a signal those cells release, using four special tubes. If your school or employer names a specific TB test, check its requirements before choosing.

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