Mycobacterium tuberculosis by QuantiFERON TB Gold Plus, Incubated

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
Other See note  Note: External clients must be pre-approved by testing laboratory manager to collect and submit specimens (800-628-6816 or 216-444-5755). Four special Qiagen collection tubes must be drawn. Do not collect using a line draw. Tubes must be incubated and processed per the protocol in Special Information section.


Environmental Condition Description
AmbientRefer to Special Information.
Refrigerated28 days

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. 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. Refer to the manufacturer’s instructions for use if outside this altitude. 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. Following labeling, filling and shaking, the tubes must be transferred to a 37°C ± 1 °C incubator as soon as possible, and within 16 hours of collection. Prior to incubation, maintain tubes at room temperature (22 °C ± 5 °C [71.6 °F ± 9 °F]). If QFT - Plus Blood Collection Tubes are not incubated at 37 °C directly after blood collection and shaking, invert the tubes to mix 10 times prior to incubation at 37 °C. Incubate the QFT - Plus Blood Collection Tubes UPRIGHT at 37 °C ± 1 °C for 16 to 24 hours. The incubator does not require CO2 or humidification. After incubation of the blood collection tubes at 37 °C ± 1 °C, tubes may be held between 4 - 27 °C for up to 3 days prior to centrifugation. After incubation of the tubes at 37 °C ± 1 °C, harvesting of the plasma is facilitated by centrifuging tubes for 15 minutes at 2000 to 3000 RCF (g). The gel plug will separate the cells from the plasma. If this does not occur, the tubes should be re-centrifuged. Samples can be stored in centrifuged QFT - Plus Blood Collection Tubes for up to 28 days at 2 - 8 °C.

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).