Mycobacterium tuberculosis by QuantiFERON TB Gold Plus

Test Mnemonic


CPT Codes

  • 86480 - QTY (1)




  • TB Result
  • TB1 Antigen minus Nil Result
  • TB2 Antigen minus Nil Result
  • Mitogen minus Nil Result
  • TB Interpretation
  • NIL Result

Performing Laboratory

Cleveland Clinic Laboratories

Specimen Requirements

Volume Type Container Collect Temperature Transport Temperature Special Instructions
N/ASee noteSee note AmbientFour special tubes (QuantiFERON Gold PLUS tubes only) must be drawn: Grey cap with white ring (Nil control); Green cap with white ring (TB1 Ag); Yellow cap with white ring (TB2 Ag); Purple cap with white ring (Mitogen Control). Tubes must be kept at ambient temperature until received in the testing laboratory. DO NOT CENTRIFUGE. See Special information section. Samples collected on Saturday or Sunday must be received at Cleveland Clinic Laboratories by 11:00 p.m. See Special Information section.


Environmental Condition Description
AmbientRefer To Special Information
Refrigerated Unacceptable
Frozen Unacceptable

Days Performed

Mon - Sun

Turnaround Time

2 - 3 days


Name Description
Chemiluminescence Immunoassay (CLIA) 

Reference Range

TB Interpretation
Sex Age From Age To Type Range Range Unit
       NormalNo evidence of current or previous infection with Mycobacterium tuberculosis 
TB1 Antigen minus Nil Result
Sex Age From Age To Type Range Range Unit
TB2 Antigen minus Nil Result
Sex Age From Age To Type Range Range Unit

Special Info

External clients must be pre-approved to collect and submit specimens. Please refer any requests from outside laboratories to Client Services at 800-628-6816 or 216-444-5755. Specialized blood collection tubes are required. Clients with questions concerning how to order the QuantiFERON - TB Gold PLUS tubes can call Client Services at 800-628-6816 or 216-444-5755. Request QuantiFERON - TB Gold PLUS tubes on the Supply Storefront available at our website Blood collection tubes should be at room temperature 17 - 25 °C (62.6 - 77 °F) at the time of blood collection. For each patient, collect 1 mL of blood by venipuncture directly into each of the QFT - Plus Blood Collection Tubes. This procedure should be performed by a trained phlebotomist. As 1 mL tubes draw blood relatively slowly, keep the tube on the needle for 2 - 3 seconds once the tube appears to have completed filling. This will ensure that the correct volume is drawn. The black mark on the side of the tubes indicates the validated range of 0.8 - 1.2 mL. If the level of blood in any tube is outside of the indicator mark, a new blood sample should be obtained. Under or over - filling of the tubes outside of the 0.8 - 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 QFT - Plus Blood Collection Tubes being used. DO NOT COLLECT USING A LINE DRAW. QFT - Plus Blood Collection Tubes can be used up to an altitude of 2650 feet (810 meters) above sea level. HA QFT - Plus Blood Collection Tubes should be used at altitudes between 3350 and 6150 feet (1020 and 1875 meters). If using QFT - Plus Blood Collection Tubes outside these altitude ranges between 2650 and 3350 feet (810 and 1020 meters) or above 6150 feet (1875 meters), or if low blood draw volume occurs, users can collect blood with a syringe and immediately transfer 1 mL to each of the 4 tubes. For safety reasons, this is best performed by removing the syringe needle, ensuring appropriate safety procedures, removing the caps from the 4 QFT - Plus Blood Collection Tubes and adding 1 mL of blood to each (to the black mark on the side of the tube label which indicates the validated range of 0.8 - 1.2 mL). Replace the caps securely and mix as described below. Ensure each tube (Nil, TB1, TB2 and Mitogen) is identifiable by its label or other means once the cap is removed by the performing laboratory. Immediately after filling the tubes, shake them 10 times just firmly enough to make sure the entire inner surface of the tube is coated with blood. This will dissolve antigens on the tube walls. Over vigorous shaking may cause gel disruption and could lead to aberrant results. The tubes must be kept at room temperature and sent ASAP. DO NOT CENTRIFUGE. Tubes must reach Cleveland Clinic Laboratories at the Main Campus within 12 hours of collection.

Clinical Info

Screening test for Tuberculosis (TB)

Clinical Limitation

Inaccurate or indeterminate results may occur if adherence to collection instructions are not followed. Grossly hemolyzed samples, lipemic samples, and samples containing particulate matter or exhibiting obvious microbial contamination will be rejected. Bacterial contamination or heat inactivation of samples may affect the results. Heterophilic antibodies in human serum can react with reagent immunoglobulins, interfering with in vitro immunoassays. Patients routinely exposed to animals or to animal serum products can be prone to this interference and anomalous values may be observed. The performance characteristics have not been evaluated for individuals younger than 18 years, pregnant women, individuals with impaired or altered immune function or other clinical conditions (HIV infection, transplant recipients, hematological disorders, malignancies, diabetes, chronic renal failure).