#83896 Mycobacterium tuberculosis Infection Determination by QuantiFERON-TB Gold, Blood: A Quick Reference for Specimen Collection and Processing
Collection must be performed using 1 of the following kits:
- QuantiFERON-QTB Gold In-Tube Collection Kit (Supply #T628)
- QuantiFERON-QTB High Altitude Collection Kit (Supply #T649)
Note: This kit is for clients in locations with an altitude greater than 3,350 feet above sea level.
1. Collect 1-mL blood by venipuncture into each of the 3 tubes.
- Expect these tubes to fill slowly.
- Leave tube on the needle for 2–3 seconds after the flow of blood has stopped.
- When tube is upright, blood must meet the small black mark on the label.
- Use of butterfly needle is not recommended, but if necessary, first collect other required tubes or use a “purge” tube to remove the air from the line. Then proceed to collect the QTB tubes.
- These tubes are manufactured to draw 1 mL of blood and perform optimally within the range of 0.8 to 1.2 mL. (Figure 1) Underfilled or overfilled specimens will be rejected.
- If the level of blood is not close to the black indicator line, another blood specimen should be collected.
Figure 1 QTB validated fill range.
Used with permission. Cellestis Inc.
2. Immediately shake the tubes firmly for 5 seconds.
- Entire inner surface of the tube must be coated with blood. (Figure 2)
- Over energetic shaking may cause gel disruption and could lead to aberrant results.
Figure 2 Blood should coat the entire inner surface
3. Label tubes appropriately. The label should be placed below colored QuantiFERON band, so back window is visible on all 3 collection tubes.
4. Maintain tubes at room temperature until incubation.
Incubation and Centrifugation
Immediate incubation is recommended, but must be started no later than 16 hours after collection.
1.Incubate all 3 tubes upright at 37°C for 16–24 hours
- If incubation is delayed, remix tubes by inverting for 5 seconds immediately before starting incubation (hemolyzed plasma is acceptable).
- Improper incubation may cause erroneous results.
- Humidity and CO2 not required.
2. Centrifuge tubes for 15 minutes at 3000 RCF (g) after incubation.
3. Place all 3 tubes in the QTB Transport bag (supplied). (Figure 3)
Figure 3 QTB transport kit
4. Store refrigerated at 2°C to 8°C.
- Specimens are stable for 28 days when refrigerated.
Ship QTB kit at refrigerated temperature (2°C–8°C). (Figure 3)