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Test Code QuantiFERON TB Gold Plus Quantiferon TB Gold Plus

Important Note

Special collection, incubation, and centrifugation procedures must be followed.

Must use the QuantiFERON TB Gold Plus Collection Kit (4 Tubes Gray, Green, Yellow, Purple)

Ordering Guidance

This test is not recommended for use for diagnosis of active tuberculosis (TB) infection. It can be used as an aid to detect latent TB infection. This is an Indirect test for Mycobacterium tuberculosis infection, to be used in conjunction with risk assessment, radiography, and other medical and diagnostic evaluations

Specimen Collection

  1. Special collection, incubation, and centrifugation procedures must be followed.
  2. Must use the QuantiFERON TB Gold Plus Collection Kit (4 Tubes Gray, Green, Yellow, Purple) to collect whole blood.
  3. If butterfly is used, collect other required tubes FIRST
  4. If butterfly is used and no other tests ordered, use a waste tube first then fill tubes 
  5. Make sure blood level is within the black bar on each tube, preferably near the top of the black bar.  
  6. The color of the tube is displayed on the label. Please ensure that the color on the label matches the color of the tube.
  7. Orient the labels so that the patient's name is at the top of the tube.

 

Beebe Healthcare Laboratory Services Note:

Tubes fill slowly

Immediately after collection: SHAKE the tubes firmly 10 times.

The entire inner surface of the tubes must be coated with blood.

Maintain tubes at room temperature until the incubation phase. Do not refrigerate or freeze.

Incubation of the 4 tubes must be started within 16 hrs of collection.

Specimen Minimum Volume

1 mL in each tube. Blood volume must fall within the black bar displayed on the tube.

Specimen Stability

Once tubes are centrifuged, the specimen is stable for 28-days refrigerated at 2°C to 8°C.

Reference Value

Negative

Day(s) Performed

Tuesday and Thursday

Interpretation

A single positive result by this test should not be used solely to diagnose latent tuberculosis (TB). Results should be used in conjunction with risk assessment, radiography, and other medical and diagnostic evaluations.

 

Positive:

Interferon-gamma (IFN-gamma) response to Mycobacterium tuberculosis antigens detected, suggesting infection with M tuberculosis. Positive results in patients at low-risk for TB should be interpreted with caution and repeat testing on a new sample should be considered as recommended by the 2017 American Thoracic Society, the Infectious Diseases Society of America, the Centers for Disease Control and Prevention (ATS/IDSA/CDC) Clinical Practice Guidelines for Diagnosis of Tuberculosis in Adults and Children.(1) False-positive results may occur in patients with prior infection with Mycobacterium marinum, Mycobacterium szulgai, or Mycobacterium kansasii.

 

Negative:

No IFN-gamma response to M tuberculosis antigens was detected. Latent infection with M tuberculosis is unlikely. A single negative result does not exclude infection with M tuberculosis. In patients at high risk for M tuberculosis infection, a second test should be considered in accordance with the 2017 ATS/IDSA/CDC Clinical Practice Guidelines for Diagnosis of Tuberculosis in Adults and Children.(1)

 

Indeterminate due to Low Mitogen Value:

Indeterminate results due to a low IFN-gamma level in the mitogen (positive control) tube. This may occur due to a low lymphocyte count, reduced lymphocyte activity, or inability of the patient's lymphocytes to generate IFN-gamma.

 

Indeterminate due to High Nil value:

Indeterminate results due to a high level of IFN-gamma in the Nil (negative control) tube. This may occur due to heterophile antibody effects or nonspecific, circulating IFN-gamma in the patient's blood sample. Repeat testing on a new specimen is suggested

CPT Code

86480

Performing Location

Margaret H. Rollins Campus Laboratory