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Catalog ID QFT QuantiFERON TB Gold in Tube

Important Note

QFT is no longer performed at AUMC Clinical Pathology.  Order Ref T-Spot if clinically indicated.

Please see link for Ref T-Spot for complete ordering details.

CPOE Test Name

QFT, Quantiferon-TB Gold

Synonyms

M. tuberculosis Infection Determination, QuantiFERON TB, IGRA, Inteferon Gamma Release Assay

Specimen Type

Plasma

Specimen Requirements

QuantiFERON Collection Kit only; Available in Receiving Laboratory (BI 2029) All 3 tubes in the kit MUST be used and collected correctly.

Special Instructions Please read before collecting blood

• As 1 mL tubes draw blood relatively slowly, keep the tube on the needle for two to three seconds once the tube appears to have completed filling to ensure that the correct volume is drawn.

• The black mark on the side of the tubes indicates the 1mL fill volume. The blood collection tubes are manufactured to draw 1 mL ±10 percent and perform optimally within the range of 0.8 to 1.2 mL. If the level of blood in any tube is not close to the indicator line, it is recommended that another blood sample be collected using a syringe and 1mL transferred to each of the three tubes. For safety reasons, this is best performed by removing the syringe needle, while ensuring appropriate safety procedures, removing the caps from the three QFT-Gold KIT tubes, and adding 1 mL of blood to each (to the black mark on the side of the tube label). Replace the tube caps securely and mix as described in step 2 below. Under- or over-filling the tubes outside of the 0.8 to 1.2 mL range may lead to erroneous results.

If a “butterfly needle” is being used to collect blood, a “purge” tube should be used to ensure that the tubing is filled with blood prior to the QuantiFERON®-TB Gold KIT tubes being used.

 2. Immediately after filling tubes, mix them 10 times just firmly enough to ensure that the entire inner surface of the tube is coated with blood to solubilize antigens on tube walls.

 • Over-energetic shaking may cause gel disruption and could lead to aberrant results

 

Storage and Transport

After collection, tubes are brought to the Receiving Laboratory. Tubes are re-mixed by the lab by gentle inversion 10 times, and incubated at 37° C within 16 hours of collection. Following the incubation period (16-24 hours), the tubes are centrifuged for 15 minutes at 3000 g’s. Tube set is then stored refrigerated in a designated rack until ready for testing by the Clinical Immunology Laboratory.

Causes for Rejection

Specimens other than the QTB Gold collection kit, lipemic samples, improper blood volume in tubes

Reference Range

See Interpretive Comments that are reported with each patient result.

Interpretation

Diagnosing or excluding tuberculosis disease and assessing the probability of latent tuberculosis infection requires a combination of epidemiological, historical, medical, and diagnostic findings that should be taken into account when interpreting QuantiFERON-TB Gold results.

Turn Around Time

3-5 business days from date of collection

Methodology

Cell Culture/ELISA

CPT / HCPCS Code

86480

Performing Lab

Immunology Lab BI 2011 721-3378