Quantiferon Gold

November 06, 2017

NorDx is pleased to announce the offering of Quantiferon Gold (QTB) test for tuberculosis through Mayo Medical Laboratories, available November 1, 2017. T-SPOT® at Oxford Diagnostics and other TB testing through the Maine State Lab will be phased out by the end of November. QTB testing allows greater flexibility in collection times as well as interfaced results which will ensure tests are  reported timely and accurately.

Special collection tubes are required for testing. Clients wishing to draw their own samples may obtain sample kits by completing a NorDx Supply Requisition. NorDx couriers will deliver the collection kits within 72 hours. 

A special collection kit is required for Quantiferon Gold Testing.
Highlights are: 
3 tubes to be filled 1 mL each – draw after 7 am Mon-Fri
Fill to line
Invert 10 times
Transport to lab at room temperature

Collect samples after 7 a.m. Monday through Friday ONLY and deliver to NorDx for processing, via your normally scheduled courier. Results will be reported within one week of collection.  

QuantiFERON-TB Gold (QFT) ELISA Testing
QuantiFERON-TB Gold (QFT) is an indirect test for M. tuberculosis infection (including disease) and is intended for use in conjunction with risk assessment, radiography, and other medical and diagnostic evaluations.

QFT is an in vitro diagnostic test using a peptide cocktail simulating ESAT-6, CFP-10 amd TB7.7 proteins to stimulate cells in heparainized whole blood.  Detection of interferon-y (IFN-y) by enzyme-linked  immunosorbent assay (ELISA) is used to identify in vitro responses to those peptide antigens that are associated with TB infection.

1. Test code in SCC is QFTB.
2. Obtain a Quantiferon (QTB) collection kit.
a. One kit is needed for each patient to be tested.
b. Kits may be ordered on a supply requisition.  Write in number of “Quantiferon” kits desired (1 kit per patient).  
3. Samples can be collected after 7am Monday through Friday and must be delivered to Scarborough by 10pm for processing.  Avoid days prior to major holidays.
4. For each person to be tested, collect 1 mL of blood by venipuncture directly into each of the 3 QFT blood collection tubes:
a. QuantiFERON Nil tube – gray cap with white ring
b. TB Antigen tube – red cap with white ring
c. QuantiFERON Mitogen tube – purple cap with white ring
d. Tubes have a black mark on the side of the tube label to designate the 1 mL fill point. 
e. Tubes are to be used between sea level and 810 meters. Special tubes are available for high altitudes. High altitude tubes will have yellow instead of white rings and may be used between 1020 and 1875 meters.
5. For optimal results:
a. Tubes draw 1 mL relatively slowly. Keep tube on needle for 2-3 seconds once the tube appears to have completed filling to be sure the correct volume is drawn.
b. For difficult draws, low volume fill collects and altitudes between those specified for the tubes, blood can be collected using a syringe and transferring 1 mL immediately to each tube.  For safety reasons, this is best performed by removing the needle from the syringe and caps from the tubes and adding 1 mL to each tube (to the black mark on the label).  Replace caps and mix (see #3 below).  
c. If a butterfly needle is used, a purge tube must be used first to remove the air.
d. Tubes are validated to collect between 0.8 – 1.2 mL as indicated by the black mark on the side of the tube.  If the blood level in any tube is not close to the indicator line, obtain another blood sample.
e. Tubes should be 17 – 25 C at the time of collection.
6. Immediately after filling tubes, invert them ten (10) times just firmly enough to ensure that the entire inner surface of the tube is coated with blood to dissolve antigens on the tube wall.  Over-energetic shaking may cause gel disruption and could lead to aberrant results.  
7. Label each tube appropriately.  
a. Collection time must be documented.  
b. Labels are to be placed below the colored QuantiFERON band so back window is visible on all three collection tubes and type of tube must be identifiable after cap is removed.
8. Do NOT spin tubes.  Tubes must be incubated prior to centrifugation.  
9. Tubes must be transferred to Scarborough for 37 C incubation as soon as possible after collection.  
a. See instructions below.  
b. Keep tubes in packaging provided.