FAQ


What is the T-SPOT.TB test?
Can I use the T-SPOT.TB test instead of the tuberculin skin test (TST)?
What are the limitations of the tuberculin skin test (TST)?
What are the advantages of the T-SPOT.TB test?
Where can I send blood specimens for the T-SPOT.TB test?
Is the T-SPOT.TB test affected by previous BCG vaccination?
How much blood do you need for the T-SPOT.TB test?
How will the T-SPOT.TB test results be reported?
What do I do with a Borderline test result?
What do I do with an Invalid test result?
Is the T-SPOT.TB test covered by insurance?
Which blood collection tubes do I use?
Can I use blood collection tubes that contain EDTA?
What is the sensitivity and specificity of the T-SPOT.TB test?

 

What is the T-SPOT.TB test?

The T-SPOT.TB test is a blood test, also known as an Interferon Gamma Release Assay, or IGRA, for TB infection. The test was approved by the FDA in 2008. The T-SPOT.TB test is an in vitro diagnostic test that enumerates the response of effector T cells that have been senstitized to Mycobacterium tuberculosis. The
T-SPOT.TB test is an indirect test for M. tuberculosis infection (including disease) and is intended for use in conjunction with risk assessment, radiography and other medical and diagnostic evaluations.¹

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Can I use the T-SPOT.TB test instead of the tuberculin skin test (TST)?

Yes. The Centers for Disease Control and Prevention (CDC) state in their updated guidelines that IGRAs (e.g. the T-SPOT.TB test) may be used in place of a TST in most situations requiring TB testing.² The CDC states that IGRAs are preferred for BCG vaccinated individuals and for those persons who are unlikely to return for the reading of the test result.² In addition, the CDC states that the administrative and logistic difficulties associated with the skin test make IGRAs an attractive diagnostic aide for detecting TB.²

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What are the limitations of the Tuberculin Skin Test (TST or PPD)?

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What are the advantages of the T-SPOT.TB test?

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Where can I send blood specimens for the T-SPOT.TB test?

Oxford Diagnostic Laboratories®, the only national TB testing service exclusively dedicated to performing the T-SPOT.TB test, has the ability to set up your facility through a simple process. Please contact Client Services at 1-877- 59 TBLAB to get started.

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Is the T-SPOT.TB test affected by previous BCG vaccination?

Unlike the TST, there is no association with BCG vaccination and T-SPOT.TB test results.¹ The test utilizes two M. tuberculosis specific antigens (ESAT-6 and CFP-10) that do not cross react with the BCG vaccine or most common non-tuberculosis mycobacteria (NTMs).

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How much blood do you need for the T-SPOT.TB test?

The guidelines for the volume of blood are:

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How will T-SPOT.TB test results be reported?

The T-SPOT.TB test results will be reported as positive, negative, borderline, or invalid. Spot counts are also reported.

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What do I do with a Borderline?

Borderline results are clinically meaningful and should be followed. Retesting by collecting another sample is recommended.

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What do I do with an Invalid test result?

Invalid results are not clinically interpretable and may occur if the positive and/or negative controls do not perform as expected. Retesting by collecting another sample is recommended.

Invalid results are uncommon and may be related to the immune status of the individual or a number of technical factors.

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Is the T-SPOT.TB test covered by insurance?

Yes, the T-SPOT.TB test is covered by most insurance. The test is covered by a unique CPT® code: 86481

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Which blood collection tube should be used?

Collect the blood specimen(s) in a standard green top tube (lithium or sodium heparin). No special collection tubes are required.

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Can I use blood collection tubes that contain EDTA?

EDTA affects the secretion of interferon gamma. Blood collection tubes that contain this anti-coagulant cannot be used.

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¹T-SPOT.TB Package Insert
²CDC MMWR 2010;59 (No.RR-5): 1-25
CPT is a registered trademark of the American Medical Association
T-SPOT and Oxford Diagnostic Laboratories are registered trademarks of Oxford Immunotec Ltd.

>Note: For immunocompromised individuals, collect double the recommended blood volume.