Table 3.

Take-Home Points

IGRA can be used in any evaluation for tuberculosis infection (active or latent).
IGRA are more specific than TSTs, which may be positive because of previous BCG vaccination or exposure to non-tuberculosis Mycobacterium.
A positive IGRA indicates tuberculosis infection but does not differentiate between active or latent infection.
A negative IGRA excludes tuberculosis in immunocompetent patients.
Immunosuppressed patients are more likely to have indeterminate results.
IGRA does not require a second visit to read the results.
IGRA is more costly and requires processing within 12 hours of collection.
  • IGRA, interferon gamma release assays; TST, tuberculin skin test; BCG, Bacillus Calmette-GuĂ©rin.