Interferon Gamma Release Assay (Quantiferon)
- Description
- Interferon Gamma Release Assays identify individuals with latent TB to enable treatment.
- Clinical details
- QFTB QuantiFERONâ„¢-TB Gold Plus is an indirect test for latent M. tuberculosis infection (LTBI) and M. tuberculosis complex infection. It is recommended for routine screening, contact studies and in patients with normal lymphocyte counts. In lymphopenic or immunosuppressed patients, or small volume paediatric samples (<4 mls blood) the alternative interferon gamma release assay, T-SPOT.TB test is recommended. TSTB T-SPOT.TB Gold is an indirect test for latent M. tuberculosis infection (LTBI) and M. tuberculosis complex infection. It is recommended for use in lymphopenic or immunosuppressed patients, or small volume paediatric samples (<4 mls blood). An alternative test, QuantiFERONâ„¢-TB Gold Plus, is recommended for use in all patients with normal lymphocyte counts.
- Related condition
- Reference range
QFTB: <0.35
TSTB: ≥5
- Units
- QFTB: IU/ml TSTB: spots
- Synonyms
- Quantiferon, T-spot, tspot, t spot
- Testing site
- Synnovis : Reference Services : Blackfriars Hub
- Laboratory
- Diagnostic Immunology
- Sample type and volume required
- QFTB: Lithuim Heparin (green top) 6ml , TSTB: Lithium heparin (green top or orange screw cap paediatric blood collection tubes) Adults and children ≥ 10 years of age: 6 mL Children ≥2 to <10 years of age: 4 mL Children <2 years of age: 2 mL
- Special sample instructions
QFTB
Samples kept at room temperature must be received in the Immunology lab within 12 hours and by 4pm on the day of venepuncture.
Samples kept at 4C, received in the Immunology lab within 53 hours of venepuncture and by 4pm on the day of delivery.
TSTB
Samples kept at room temperature must be received in CSR in the ODL courier collection box within 24 hours of venepuncture and by 6pm.
- Turnaround time
- QFTB: 7 days TSTB: 10 days Please Note: There is no laboratory service offered over bank holidays and weekends. Samples received in these periods will not be processed