TUBERCULOSIS - GAMMA INTERFERON -QUANTIFERON(TB)
^HOW TO READ YOUR TEST
NIL TUBE in IU/mL ANTIGEN TUBE MINUS NIL TUBE RESULT INTERPRETATION
< = 10 <0.35 Negative M. tuberculosis infection unlikely
> = 0.35 &<25% of Nil tube Negative M. tuberculosis infection unlikely
> = 0.35 &> = 25% of Nil tube Positive* M. tuberculosis infection likely
>10 Any result Indeterminate This may be due to excessive levels of circulating gamma interferon orpresence of heterophile ab.
COMMENT: A Quantiferon test is considered positive for IFN-response to the TB Antigen that is significantly above the baseline IFN-IU/ml value.The
itogen-stimulated plasma sample serves as an IFN-positive control for each specimen tested.A low response to Mitogen
^NOTE:
1.This assay cannot differentiate between Latent infection and Active Tuberculosis.
2. Magnitude of measured Gamma Interferon cannot be correlated with stage or degree of infection,level of immune responsiveness or likelihood of progression to active disease.
3.False negative results maybe obtained if sample is taken prior to development of immune response.CDC recommends repeat test after 8-10 weeks
in case of high suspicion of tuberculosis.
4. Patients with impaired immune function or undergoing therapy,such as HIV patients or patients undergoing immunosuppression after organ
transplantation can also show false negativity.
5.Negative result does not preclude the possibility of Mycobacterium tuberculosis infection / disease
6. Heterophilic antibodies and rheumatoid factors in samples may interfere with test results.
