Laboratory Test Detail

Last Updated: July 22, 2024 @ 9:13 am


T-SPOT, Tuberculosis (TB)

  • Two Green Top (Li Heparin)
  • Two 4 mL (Min:3 mL) Whole blood in Green Top (Li Heparin). Submit Ambient.

Also Acceptable:
  • One 10 mL (Min:6 mL) Whole blood in Green Top (Li Heparin). Submit Ambient.
Special Handling:
  • Sample can only be collected MONDAY-FRIDAY.
    Immunocompromised patients will require Four 4 mL Lithium Heparin tubes (minimum 12 mL).
    Call Pendleton Client Service Department for any extenuating circumstances.
Rejection Criteria:
  • EDTA, Oxalate, Citrate
  • Less than 4mL
    Specimens must arrived in Pendleton to be processed within 32 hours of collection.
    Critical Ambient
Stability:Ambient: 32 Hour(s); Refrigerated: Unacceptable; Frozen: Unacceptable; Incubated: Unacceptable
  • Enzyme-linked Immunospot (ELISPOT)
  • Interferon-Gamma Release Assay (IGRAs)
Performed:Tuesday, Wednesday, Thursday, Friday, Saturday
Reported:2-3 Day(s)
CPT Codes:
  • 86481
Interpretive Data:Please see report for interpretive data.

NEGATIVE - The test result is NEGATIVE if both (Panel A minus Nil Control) and (Panel B minus Nil Control) are less than or equal to 4. This includes values less than zero.

POSITIVE - The test result is POSITIVE if (Panel A minus Nil Control) and/or (Panel B minus Nil Control) is greater than or equal to 8.

BORDERLINE - The test result is BORDERLINE if (Panel A minus Nil Control) or (Panel B minus Nil Control) is equal to 5, 6, or 7. It is recommended to repeat the T-SPOT.TB testing by submitting a new specimen.

Diagnosing or excluding tuberculosis disease, and assessing the probability of LTBI, requires a combination of epidemiological, historical, medical and diagnostic findings that should be taken into account when interpreting T-SPOT.TB test results. Refer to the most recent CDC guidance ( for detailed recommendations about diagnosing TB infection (including disease) and selecting persons for testing.

The performance of T-SPOT.TB has not been adequately evaluated with specimens from individuals younger than 17 years, in pregnant women, and in patients with hemophilia.

A false positive result was obtained for T-SPOT.TB when tested in subjects with M. xenopi, M. kansasii and M. gordonae. While ESAT-6 and CFP10 antigens are absent from BCG strains of M. bovis and from most environmental mycobacteria, it is possible that a positive T-SPOT.TB result may be due to infection with M. kansasii, M. szulgai, M. gordonae or M. marinum. Alternative tests would be required if these infections are suspected.

A negative test result does not exclude the possibility of exposure to, or infection with M. tuberculosis. Patients with recent exposure to TB infected individuals exhibiting a negative T-SPOT.TB result should be considered for retesting within 6 weeks or if other relevant clinical symptoms indicate possible infection.

A positive test result does not rule in active TB disease; other tests should be performed to confirm the diagnosis of active TB disease such as sputum smear and culture, PCR, and chest radiography.

T-SPOT.TB has not been evaluated in subjects who have received >1 month of anti-TB therapy.
  • 2862 - NIL (NEG) CONTROL
  • 2863 - PNL A SPOT COUNT
  • 2864 - PNL B SPOT COUNT
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