Tuberculosis Blood Test

Detect tuberculosis bacteria in the body. This test is for those who have been exposed to tuberculosis bacteria (Mycobacterium tuberculosis); require evidence of a negative tuberculosis test; or are at high risk for contracting tuberculosis. Read more

Test details

Sample type:

Blood

Preparation:

You do not need to do anything special to prepare for the sample collection. Fasting is not required for this test.

Test type: In Person

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$149.00

+ $6.00 Physician Service Fee

Quantity

What

Detect Mycobacterium tuberculosis, the bacteria that causes Tuberculosis (TB). This is detected in both active TB and latent TB.

Who

Must be 18+ years of age to purchase.

How

Blood

Where

Find a location near you

Schedule an appointment, then visit one of the Quest Diagnostics Patient Service Centers

About the Test

This test is an Interferon-Gamma Release Assays (IGRAs) whole-blood test that detects the immune system’s response to M. tuberculosis. M. tuberculosis, or TB bacteria, usually attack the lungs. However, TB bacteria can attack any part of the body such as the spine, kidneys, and brain. In fact, not everyone that becomes infected with TB bacteria will become sick. As a result, two TB-related conditions exist: latent TB infection (LTBI) and TB disease. If not treated properly, TB disease can be fatal. This test does not differentiate between latent tuberculosis infection (LTBI) and active TB disease.

LTBI is a carrier state of TB that can last for weeks, months, or years before developing into TB disease. Active TB is when tuberculosis bacteria overwhelm a person's immune system, and symptoms start to appear. The Tuberculosis Blood Test helps detect the presence of M. tuberculosis and can be a first step in the process of determining is someone has latent TB infection or TB disease. Further testing may be required if the blood test is positive.

This test may be right for you if you:

Have been exposed to a person with a current or past TB infection
Are from a TB-endemic country (including most countries in Latin America, the Caribbean, Africa, Asia, and Eastern Europe, and Russia)
Work in high-risk settings, including prisons, healthcare settings, or homeless shelters
Are HIV positive or have another medical condition that weakens your immune system
Have an injection drug substance use disorder
Need evidence of a negative Tuberculosis test for back-to-school, back-to-work, or international travel

This is a QuantiFERON-TB Gold Plus Assessment, a blood test that aids in the detection of M. tuberculosis bacteria (MTB). Instead of antibodies, it measures a cell-mediated immune (CMI) response to T-cells. CMI is an important component of the body's defense against certain diseases. This test helps to determine when CMI has been activated. Most blood tests examine if antibodies were produced in response to exposure. However, the Tuberculosis Blood Test examines the T-cells that are essential for fighting bacterial infections. Due to this, people vaccinated with the bacillus Calmette-Guérin (BCG) TB vaccine or infected with most environmental mycobacteria should test negative with this blood test.

Understanding your results: The QuantiFERON-TB Gold Plus will provide a positive or negative result. If positive for the bacteria, further testing is necessary to determine whether you have a latent TB infection (LTBI) or TB disease. This test can also provide negative results for those who have received the BCG TB vaccine or have been exposed to environmental mycobacteria.

Symptoms of an active TB infection may include:

Chronic cough
Chest pain
Fever
Unexplained weight loss
Fatigue
Weakness
Night sweats
Coughing up blood

You must be 18 years of age or older to purchase. Purchases not permitted in: AK, AZ, HI.

You do not need to do anything special to prepare for the sample collection. Fasting is not required for this test.

When your results are ready, we will send them to you in a clear, easy-to-read report. You will have the option to consult with an independent physician to discuss your results. Together, you can determine the next best steps for your care. Your test results will be available to you a few days after we collect your sample.

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Easy to buy & simple to schedule

After your purchase, schedule an appointment at a nearby Quest Diagnostics location and have your specimen sample collected by a trained healthcare professional.

Fast online results, with support

Access test results from your phone as soon as they’re available, with the option to discuss your results with an independent physician at no extra cost.

Your results are available on our free, secure patient portal that you can access on your smartphone, tablet, or desktop. You will receive an email notification when your results are ready. You can also share your results with your healthcare provider, family, or friends.

Without treatment, 1 in 10 people with a latent tuberculosis infection will develop TB disease.**

Learn about the two types of tuberculosis tests and how newer blood tests offer much higher accuracy than traditional skin tests.

FAQs

What are the advantages of the QFT-Plus blood test over the Tuberculin Skin Test (TST)?

The results are either positive or negative, and have a lower risk of reader bias when compared to a skin test
Accuracy is not affected by a prior bacillus Calmette-Guérin (BCG) TB vaccination
Only requires a single patient visit (2 to 4 are required for the TST)

Does a previous TST affect the QFT-Plus blood test result?

No, a prior TST does not boost, or provide a false positive for IGRA results, however a previous infection may.

Do vaccinations affect a QFT-TB Gold Plus result?

Live-virus vaccines may affect IGRA test results. However, the effect of live-virus vaccination on IGRAs has not been studied. Until more information is available, the CDC recommends that IGRA testing for live-virus vaccinations are performed as follows:

Either on the same day as a live-virus vaccination or 4 to 6 weeks after the administration of a live-virus vaccination
At least 1 month after a smallpox vaccination

You should not delay a COVID-19 vaccination due to testing for TB. The COVID-19 vaccine is not a live-virus vaccine. It does not affect the results of the TB blood test.

Our references

^*Data and Statistics. https://www.cdc.gov/tb/statistics/default.htm

^**Tuberculosis (TB) https://www.cdc.gov/tb/

Tuberculosis Blood Test