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Test Code QFT4 QuantiFERON-TB Gold Plus, Blood

Important Note

Use of syringe may insure correct blood volume

  • If butterfly is used, collect other required tubes FIRST
  • If butterfly is used and no other tests ordered, use a waste tube first then fill tubes 
  • Make sure blood touches the black line in each tube
  • There are now 4 tubes in the kit, instead of 3 as indicated below

 

 


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.



Specimen Required


Supplies:

-QuantiFERON-TB Gold Plus Collection Kit (T794)

-QuantiFERON-TB Gold Plus HIGH ALTITUDE Collection Kit (T795)

Collection Instructions:

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

2. For blood collection options (1-tube collection or 4-tube collection) and specimen transport instructions, see Mycobacterium tuberculosis Infection Determination by Quanti-FERON-TB Gold Plus Collection and Processing Instructions (T688).


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.

Useful For

Indirect test for Mycobacterium tuberculosis infection, to be used in conjunction with risk assessment, radiography, and other medical and diagnostic evaluations

 

This test is not recommended for use for diagnosis of active tuberculosis infection.

Method Name

Chemiluminescence Immunoassay (CLIA)/Enzyme-Linked Immunosorbent Assay (ELISA) as appropriate

Reporting Name

QuantiFERON-Tb Gold Plus, B

Specimen Type

Whole blood

Specimen Minimum Volume

4 mL: 1 mL per tube (4 tubes)

Specimen Stability Information

Specimen Type Temperature Time Special Container
Whole blood Refrigerated 28 days QTBKIT

Reference Values

Negative

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.

Clinical Reference

1. Lewinsohn DM, Leonard MK, LoBue PA, et al. Official American Thoracic Society/Infectious Diseases Society of America/Centers for Disease Control and Prevention Clinical Practice Guidelines: Diagnosis of tuberculosis in adults and children. Clin Infect Dis. 2017;64(2):111-115

2. Moon HW, Gaur RL, Tien SSH, Spangler M, Pai M, Banaei N. Evaluation of QuantiFERON-TB Gold Plus in health care workers in a low-incidence setting. J Clin Micobiol. 2017;55(6):1650-1657

3. Telisinghe L, Amofa-Sekyi M, Maluzi K, et al. The sensitivity of the QuantiFERON-TB Gold Plus assay in Zambian adults with active tuberculosis. Int J Tuberc Lung Dis. 2017;21(6):690-696

4. Theel ES, Hilgart H, Breen-Lyles M, et al. Comparison of the QuantiFERON-TB Gold Plus and QuantiFERON-TB Gold In-Tube Interferon Gamma Release Assays in patients at risk for tuberculosis and in health care workers. J Clin Microbiol. 2018;56(7):e00614-e00618. doi:10.1128/JCM.00614-18

Day(s) Performed

Monday through Friday

Report Available

2 to 5 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test Classification

This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information

86480

LOINC Code Information

Test ID Test Order Name Order LOINC Value
QFT4 QuantiFERON-Tb Gold Plus, B 71775-1

 

Result ID Test Result Name Result LOINC Value
QFTQ2 QuantiFERON-Tb Gold Plus Result 71773-6
DEXQE TB1 Ag minus Nil Result 64084-7
DEXQF TB2 Ag minus Nil Result 88517-8
DEXQG Mitogen minus Nil Result 71774-4
DEXQH Nil Result 71776-9

Forms

If not ordering electronically, complete, print, and send 1 of the following forms with the specimen:

-General Request (T239)

-Infectious Disease Serology Test Request (T916)

-Microbiology Test Request (T244)