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QuantiFERON®-TB Gold Plus (Client Incubated)

CPT: 86480
Updated on 06/16/2021
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Synonyms

  • Interferon-gamma Release Assay (IGRA) for Mycobacterium tuberculosis
  • QFT-Plus

Special Instructions

This test is time-sensitive. Specimens must be incubated at 37°C for 16 to 24 hours prior to transport to LabCorp and specimens must be received in the laboratory within 70 hours after incubation by the client (no more than 94 hours from the time of collection). Specimen collection times will be dependent on logistics from the incubating location to a LabCorp lab.

To submit QuantiFERON-TB Gold Plus specimens that are not client incubated prior to submission, order QuantiFERON®-TB Gold Plus (Test No. 182879).


Expected Turnaround Time

2 - 5 days


Related Documents

For more information, please view the literature below.

TB or not TB?

Microbiology Specimen Collection and Transport Guide


Specimen Requirements


Specimen

Whole blood


Volume

1 mL x four tubes in QuantiFERON-TB Gold Plus kit


Minimum Volume

1 mL x four tubes in QuantiFERON-TB Gold Plus kit


Container

The QuantiFERON®-TB Gold Plus collection kit contains the instructions for the collection and handling of (one each): (1) gray-top (with white ring), uncoated (nil); (2) green cap with white ring, TB1 tube; (3) yellow cap with white ring, TB2 tube; (4) purple top with white ring, mitogen-coated. A high altitude kit is also available for locations between 3350 and 6150 feet; a cap with a yellow ring differentiates the tubes.


Collection

Blood collection tubes should be at room temperature at the time of collection. Refer to collection instructions included with draw kit. Special specimen collection kit contains four gel-barrier tubes as noted above. All four tubes are required for a single test result. Each tube is designed to draw only 1 mL and fill time may be longer than other blood collection tubes. Because of the limited vacuum in these tubes, use a needle and holder (not a butterfly) to collect QuantiFERON® specimens. If a butterfly is required, first collect other required tubes or use another Vacutainer® tube to purge the butterfly line of air and then proceed with drawing the QuantiFERON tubes. Fill tubes to the black fill line on the tube. If tubes are underfilled or overfilled (see kit insert), immediately collect a replacement tube.

Following proper fill, label the tubes appropriately and shake tubes 10 times firmly enough to ensure the entire surface of the tube is coated with blood cells to solubilize the antigen on the tube walls. After shaking, the volume may fall below the fill line. Do not centrifuge or refrigerate specimens.

Return each of the four properly filled, labeled, and shaken tubes to the box labeled "QFT kit." Seal the top by removing tape from the adhesive.


Storage Instructions

Before incubation at 37°C, maintain specimen at room temperature. Stability: Kit must be incubated within 16 hours of collection.

After incubation, maintain specimen at room temperature (17°C to 27°C). Do not centrifuge, refrigerate, or ship tubes on ice.


Causes for Rejection

Grossly hemolyzed, icteric, or lipemic samples; expired collection tubes; specimen centrifuged, refrigerated, or frozen; specimen more than 94 hours old on receipt by lab; receipt of three tube collection kit; under-filled or over-filled tubes; tubes that do not yield sufficient plasma for testing

Grossly hemolyzed, icteric, or lipemic samples; expired collection tubes; specimen centrifuged, refrigerated, or frozen; specimen more than 94 hours old on receipt by lab; receipt of three tube collection kit

Grossly hemolyzed, icteric, or lipemic samples; expired collection tubes; specimen centrifuged, refrigerated, or frozen; specimen more than 94 hours old on receipt by lab; receipt of three tube collection kit; under-filled or over-filled tubes; tubes that do not yield sufficient plasma for testing


Test Details


Use

QuantiFERON-TB Gold Plus is an in vitro diagnostic test using a peptide cocktail of CD4+ and CD8+ T cell antigens to stimulate cells in heparinized whole blood. Detection of interferon-gamma by enzyme-linked immunosorbent assay (ELISA) is used to identify in vitro responses to these peptide antigens that are associated with Mycobacterium tuberculosis infection. QuantiFERON-TB Gold Plus 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.


Limitations

A negative QFT-Plus result does not preclude the possibility of M. tuberculosis infection or tuberculosis disease: false negative results can be due to stage of infection, co-morbid conditions that affect immune function, incorrect handling of the blood collection tubes following venipuncture, incorrect performance of the assay, or other individual immunological variables. Heterophile antibodies or non-specific interferon-gamma production from other inflammatory conditions may mask specific responses to CD4+ and CD8+ T cell antigens. A positive QFT-Plus result should not be the sole or definitive basis for determining infection with M. tuberculosis. Incorrect performance of the assay may cause false-positive results. A positive QFT-Plus result should be followed by further medical evaluation for active tuberculosis disease.

Although the COVID-19 mRNA vaccine is not a live virus vaccine, not enough is yet known of the potential impact of mRNA vaccines on immune responses to say conclusively whether the COVID-19 mRNA vaccine could have a potential effect on TST or IGRA test results during the first 4 weeks after COVID-19 vaccination. Visit the following CDC link for more information: https://www.cdc.gov/tb/publications/letters/covid19-mrna.html.

A negative QFT-Plus result does not preclude the possibility of M. tuberculosis infection or tuberculosis disease: false negative results can be due to stage of infection, co-morbid conditions that affect immune function, incorrect handling of the blood collection tubes following venipuncture, incorrect performance of the assay, or other individual immunological variables. Heterophile antibodies or non-specific interferon-gamma production from other inflammatory conditions may mask specific responses to CD4+ and CD8+ T cell antigens. A positive QFT-Plus result should not be the sole or definitive basis for determining infection with M. tuberculosis. Incorrect performance of the assay may cause false-positive results. A positive QFT-Plus result should be followed by further medical evaluation for active tuberculosis disease.

Although the COVID-19 mRNA vaccine is not a live virus vaccine, not enough is yet known of the potential impact of mRNA vaccines on immune responses to say conclusively whether the COVID-19 mRNA vaccine could have a potential effect on TST or IGRA test results during the first 4 weeks after COVID-19 vaccination. Visit the following CDC link for more information: https://www.cdc.gov/tb/publications/letters/covid19-mrna.html.

A negative QFT-Plus result does not preclude the possibility of M. tuberculosis infection or tuberculosis disease: false negative results can be due to stage of infection, co-morbid conditions that affect immune function, incorrect handling of the blood collection tubes following venipuncture, incorrect performance of the assay, or other individual immunological variables. Heterophile antibodies or non-specific interferon-gamma production from other inflammatory conditions may mask specific responses to CD4+ and CD8+ T cell antigens. A positive QFT-Plus result should not be the sole or definitive basis for determining infection with M. tuberculosis. Incorrect performance of the assay may cause false-positive results. A positive QFT-Plus result should be followed by further medical evaluation for active tuberculosis disease.

Although the COVID-19 mRNA vaccine is not a live virus vaccine, not enough is yet known of the potential impact of mRNA vaccines on immune responses to say conclusively whether the COVID-19 mRNA vaccine could have a potential effect on TST or IGRA test results during the first 4 weeks after COVID-19 vaccination. Visit the following CDC link for more information: https://www.cdc.gov/tb/publications/letters/covid19-mrna.html.

A negative QFT-Plus result does not preclude the possibility of M. tuberculosis infection or tuberculosis disease: false negative results can be due to stage of infection, co-morbid conditions that affect immune function, incorrect handling of the blood collection tubes following venipuncture, incorrect performance of the assay, or other individual immunological variables. Heterophile antibodies or non-specific interferon-gamma production from other inflammatory conditions may mask specific responses to CD4+ and CD8+ T cell antigens. A positive QFT-Plus result should not be the sole or definitive basis for determining infection with M. tuberculosis. Incorrect performance of the assay may cause false-positive results. A positive QFT-Plus result should be followed by further medical evaluation for active tuberculosis disease.

Although the COVID-19 mRNA vaccine is not a live virus vaccine, not enough is yet known of the potential impact of mRNA vaccines on immune responses to say conclusively whether the COVID-19 mRNA vaccine could have a potential effect on TST or IGRA test results during the first 4 weeks after COVID-19 vaccination. Visit the following CDC link for more information: https://www.cdc.gov/tb/publications/letters/covid19-mrna.html.

A negative QFT-Plus result does not preclude the possibility of M. tuberculosis infection or tuberculosis disease: false negative results can be due to stage of infection, co-morbid conditions that affect immune function, incorrect handling of the blood collection tubes following venipuncture, incorrect performance of the assay, or other individual immunological variables. Heterophile antibodies or non-specific interferon-gamma production from other inflammatory conditions may mask specific responses to CD4+ and CD8+ T cell antigens. A positive QFT-Plus result should not be the sole or definitive basis for determining infection with M. tuberculosis. Incorrect performance of the assay may cause false-positive results. A positive QFT-Plus result should be followed by further medical evaluation for active tuberculosis disease.

Although the COVID-19 mRNA vaccine is not a live virus vaccine, not enough is yet known of the potential impact of mRNA vaccines on immune responses to say conclusively whether the COVID-19 mRNA vaccine could have a potential effect on TST or IGRA test results during the first 4 weeks after COVID-19 vaccination. Visit the following CDC link for more information: https://www.cdc.gov/tb/publications/letters/covid19-mrna.html.


Methodology

Whole blood interferon-gamma test measuring responses to CD4+ and CD8+ T cell antigens


LOINC® Map

Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
182893 QFT-TB Plus (Client Incubated) 182885 QuantiFERON Criteria 8251-1
182893 QFT-TB Plus (Client Incubated) 182886 QuantiFERON TB1 Ag Value IU/mL 64084-7
182893 QFT-TB Plus (Client Incubated) 182887 QuantiFERON TB2 Ag Value IU/mL 88517-8
182893 QFT-TB Plus (Client Incubated) 182891 QuantiFERON Nil Value IU/mL 71776-9
182893 QFT-TB Plus (Client Incubated) 182892 QuantiFERON Mitogen Value IU/mL 71772-8
182893 QFT-TB Plus (Client Incubated) 182894 QuantiFERON-TB Gold Plus 71773-6

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