Tuberculosis QuantiFERON-TB Gold Plus

TEST NAME Tuberculosis QuantiFERON Gold Plus 
METHODOLOGY Detection of interferon-γ (IFN-γ) by Enzyme-Linked Immunosorbent Assay
  • QFT Log Sheet must be fully filled out for each batch of specimens and accompany all shipments.


          Test Order Code:  86480

          Test Order Description:  TB BLOOD TEST GOLD IN-TUBE

TDH DLS RequisitionPH-4182 Clinical Submission Requisition Form

Specimen Requirements

Patient Preparation

  • Quantiferon-TB Gold Plus Blood Collection 4 Tube Set (gray, green, yellow and purple).
  • Prior to collection, store Quantiferon-TB Gold Plus blood collection tubes at 4 - 25°C.
  • QFT-Plus Blood Collection Tubes should be at room temperature 17 - 25°C at the time of blood collection.
Specimen Collection
  • Refer to QuantiFERON-TB Gold Plus Package Insert for collection instructions.
  • For each patient, collect blood by venipuncture directly into each of the QFT-Plus Blood collection tubes.   If a butterfly needle is being used to collect blood, a purge tube should be used prior to QFT blood collection tubes being used.
  • Blood volume for each tube must be within black marks on side of tubes (0.8 to 1.2 mL). 
  • Gently invert the tubes 10 times.   Overly vigorous shaking may result in gel disruption and could lead to aberrant results
  • Following labeling, filling and inverting tubes must be incubated 37°C ± 1°C  within sixteen (16) hours of collection.  If unable to incubate at the collection facility, the sample must be shipped to the laboratory on the day of collection. 
  • Maintain tubes at 17 - 25°C until incubation. Gently invert tubes 10 times to remix immediately prior to incubation.
Specimen Processing
  • Incubate the tubes at 37°C ± 1°C for 16 - 24 hours.  Keep tubes upright during incubation. 
  • Tubes must be incubated prior to centrifugation. 
  • Centrifuge tubes for 15 minutes at 2000 - 3000 RCF (g).  The gel plug will separate the cells from the plasma. If no separation occurs, re-centrifuge tubes. 
  • Maintain tubes at 2 - 8°C after centrifugation until shipped.
Specimen Labeling
  • Specimen must be labeled with at least two unique patient identifiers and match accompanying QFT Log Sheet.

Specimen Storage and Preservation

  • If incubation cannot be done immediately after collection, maintain tubes at 17 - 25°C until incubation.  Then gently invert tubes 10 times prior to incubation at 37°C ± 1°C.
  • After incubation of the blood collection tubes at 37 ±1°C, tubes may be held between 4 - 27°C for up to 3 days prior to centrifugation.
  • Centrifuged specimens can be held at 2 - 8°C for up to 28 days.
Specimen Transportation
  • If tubes have been centrifuged, ship specimen set at 2 - 8°C.  
  • Ship non-incubated specimen sets at 4 - 27°C on the day of collection.
  • Keep specimen set together.  Each 4-tube specimen set must be placed in an individual biohazard bag with absorbent material.  
  • All infectious substance shipments must conform to U.S. Department of Transportation (DOT) Hazardous Materials Regulations (HMR 49 C.F.R. Parts 171-180). 
Specimen Acceptability and Rejection
  • Centrifuged specimens must be received at laboratory within 28 days of centrifugation.
  • Non-incubated specimens must be received at laboratory within sixteen (16) hours of collection.
  • Unsatisfactory specimens include, but may not be limited to

- Overfilled (more than 1.2 mL) or underfilled (less than 0.8 mL) tubes

- Specimens not maintained at 17 - 25°C prior to incubation

- Specimens not incubated within sixteen (16) hours of collection

- Specimens not centrifuged within three (3) days of incubation

- Specimens stored longer than 28 days at 2 - 8°C after centrifugation

- Specimens  that are incorrectly labeled

- Expired tubes

- Specimens incubated less than 16 hours or more than 24 hours

- Specimens incubated at greater than 37 ± 1°C.

Testing Location
  • Nashville
  • Knoxville

This Page Last Updated: September 15, 2023 at 10:57 AM