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Test Update

#83896 Mycobacterium tuberculosis Infection Determination by QuantiFERON-TB Gold, Blood: A Quick Reference for Specimen Collection and Processing


January 2010

Collection

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 butterfl y 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

Figure 1 QTB validated fill range Used with permission Cellestis Inc.

2. Immediately shake the tubes firmly for 5 seconds.

  • Entire inner surface of tube must be coated with blood.
  • Over energetic shaking may cause gel disruption and could lead to aberrant results. (Figure 2)
Figure 2

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

Figure 3 QTB transport kit

4. Store refrigerated at 2°C to 8°C.

  • Specimens are stable for 28 days when refrigerated.

Shipping

Ship QTB kit at refrigerated temperature (2°C–8°C). (Figure 3)

Questions: Call 800-533-1710 and ask for an Infectious Disease Serology Technical Specialist


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