Test Code QFTB4 / QFT4-M 
Methodology Enzyme-Linked Immunosorbent Assay (ELISA) 
Description Indirect test for Mycobacterium tuberculosis infection, to be used in conjunction with risk assessment, radiography, and other medical and diagnostic evaluations 
Specimen Supplies:
Standard Altitude: QuantiFERON-TB Gold Plus Collection Kit (T794)
High Altitude: QuantiFERON-TB Gold Plus High Altitude Collection Kit (T795) Collection
Special collection, incubation, and centrifugation procedures must be followed.
Prepare and transport specimen per QuantiFERON-TB (QFT) Gold Plus Collection and Processing Instructions (T688).

BLOOD COLLECTION (All collection tubes need to be at room temperature (1727C) at the time of draw.)
Directly into 4 Tube QuantiFERON-TB Gold Plus Kit (Preferred) -
Collect 1 mL of blood into each of 4 tubes
Tubes fill slowly.
Use of a syringe may ensure correct blood volume.
When the tube is upright, blood must meet the small black mark on the label.
If butterfly needle is used, first collect other required tubes or use a purge tube to remove the air and then proceed with collecting 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. If the level of blood is outside of the black indicator line, another blood specimen should be collected

Collection into a Single Lithium-Heparin Tube and Transfer to QFT-Blood Collection Tubes
1. Blood may be collected in a single blood collection tube containing lithium-heparin as the anticoagulant and then transferred to QFT-Plus blood collection tubes. Only use lithium-heparin as a blood anticoagulant because other anticoagulants interfere with the assay.
Label tubes appropriately. It is recommended to label the tube with the time and date of the blood collection.
Important: Blood collection tubes should be at room temperature (1725C) at the time of blood collection.
2. Fill a lithium-heparin blood collection tube (minimum volume 5 mL) and gently mix by inverting the tube several times to dissolve the heparin.
3. Following blood collection into a lithium-heparin tube, the following are options for hold time and temperatures prior to transfer of blood into the 4 QFT-Plus tubes
Option 1 Lithium-Heparin Tube Room Temperature Storage and Handling
a. Blood collected in lithium-heparin tube must be maintained at room temperature (22C 5C) for no more than 12 hours from the time of collection prior to transfer to QFT-Plus blood collection tubes and subsequent incubation.

Option 2 Lithium-Heparin Tube Refrigerated Storage and Handling Important: Procedural steps ad must be followed in sequence
a. Blood drawn into lithium-heparin tube must be held at room temperature (1725C) between 15 minutes and 3 hours after blood collection.
b. Blood drawn into lithium-heparin tube may be refrigerated (28C) for 16 to 48 hours.
c. After refrigeration, lithium-heparin tube must equilibrate to room temperature (1725C) prior to transfer to
QFT-Plus blood collection tubes.
d. Aliquotted QFT-Plus Blood Collection Tubes should be placed in the 37C incubator within 2 hours of blood
transfer. Note: If QFT-Plus Blood Collection Tubes are not incubated at 37C directly after transfer to QFT-
Plus Blood Collection Tubes, invert the tubes to mix 10 times prior to incubation at 37C. Total time from
blood draw to incubation in QFT-Plus blood collection tubes should not exceed 53 hours.
4. Transfer of blood specimen to QFT-Plus blood collection tubes:
a. Label each QFT-Plus blood collection tube appropriately. Ensure each tube (Nil, TB1, TB2 and Mitogen) is
identifiable by its label or other means once the cap is removed. It is recommended to transfer the recorded time and date of blood collection from the lithium-heparin tubes to the QFT-Plus blood collection tubes.
b. Samples must be evenly mixed by gentle inversion before dispensing into QFTPlus blood collection tubes.
c. Dispensing should be performed aseptically, ensuring appropriate safety procedures, removing the caps from
the 4 QFT-Plus blood collection tubes and adding 1 mL of blood to each tube. Replace the tube caps
securely and mix tubes well before incubation.

Incubation and Centrifugation
Notes: The following types of specimens will be rejected:
Not incubated
Not centrifuged
Received in lithium-heparin tubes
Incubation in waterbath or heat block
1. Incubate all 4 QFT-Plus tubes upright at 37C 1C for 16 to 24 hours.
2. Following incubation centrifuge for 15 minutes at 2,0003,000 RCF (g).
Hemolyzed plasma is acceptable.
3. Place all 4 QFT-Plus tubes together in the supplied QTB Transport bag (see figure 3).
4. Store refrigerate 2C to 8C. Stable 28 days refrigerated. 

Reference Values Negative 
Analytic Time 2 Days 
Day(s) Test Set Up Monday through Friday 
CPT Code(s) 86480