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Test Code TSPOT T-Spot TB Test

Important Note

The T-Spot TB test is a blood test also known as an Interferon Gamma Release Assay (IGRA), that detects the immune response of T cells found in a sample of highly purified white blood cells (WBCs) that have been sensitized to M. tuberculosis antigens. See links below to educational information about the T-Spot TB Test.

CDC IGRA Fact Sheet
Health care Worker TB Guidelines
T-Spot TB Test Bulletin

Additional Codes


PowerChart: T Spot TB

Epic: LAB1196 TB Test, Cell Immune Measure

MA Cerner: TB-T-Spot or TSPOT

Test Method

Interferon Gamma Release Assay (IGRA)

Specimen Requirement

Lithium heparin whole blood

Additional Specimen Collection Information

  • 9 year old-Adult: 9 mL lithium heparin whole blood(green-top) tube
  • Child 2-9 years old: 4 mL lithium heparin whole blood(green-top) tube
  • Child <2 years old: 2 mL lithium heparin whole blood(green-top) tube

Note: For immuno-compromised patients draw two 9 mL lithium heparin whole blood(green-top) tubes.

  1. Specimens are collected Monday through Friday 5:00 AM to 1:00PM.
  2. Specimens should not be collected on weekends or holidays.
  3. Specimen must be transported on the date collected.
  4. Courier will pick the specimens up for transport up at approximately 2 p.m. Monday through Friday.
  5. Transport at unspun ambient temperature.
  6. Specimens are stable for 32 hours at ambient temperature.
  7. Refrigerated, frozen or centrifuged specimens will be rejected by the receiving location.


Testing is performed Monday through Friday; average turn-around time is 2 days.

Reference Values

Negative: ≤ 4 spots

Note: The following results will not be flagged as abnormal since the interpretive results are reported as a comment: positive, negative, borderline or invalid. Spot counts for each well will be reported.

CPT Code Information

86481 Tuberculosis test, cell mediated immunity antigen response measurement; enumeration of gamma interferon-producing T-cells in cell suspension.

Useful For

The T-Spot TB test is a highly sensitive in vitro blood test for the diagnosis of active and latent TB. The test detects the immune response of T cells that have been stimulated by Mycobacterium tuberculosis (MTB) antigens by utilizing MTB-specfic antigens (ESAT-6 and CFP10) that are absent BCG strains and most non-tuberculosis mycobacteria. Results are unaffected by BCG vaccination and most common non-tuberculosis mycobacteria. This test can be used for all high risk groups for TB screening.

LOINC Code Information

74281-7  Mycobacterium tuberculosis stimulated gamma interferon and spot count panel - Blood