QuantiFERON TB Gold
Label Mnemonic: QTB
Epic Lab Code: LAB4485
Downtime Form: A-1a Miscellaneous Request
Commercial Mail-out Laboratory
5231 RCP
356-8593
Specimen(s):
Whole Blood
Specimen Instructions:
Testing must be arranged with Mailouts before testing can occur.
THREE specialized tubes are required, labeled: NIL, Antigen, Mitogen.

Contact Core Laboratory at (356-3527) or Mailouts at (356-8593) for the collection kit.
Collection Medium:
QuantiFERON-QTB Gold In-Tube Collection Kit
Minimum:
1 mL per tube (THREE tubes required): NIL, Antigen, Mitogen
Rejection Criteria:
Specimens other than plasma in QTB collection vials.
Delivery Instructions:
Specimen collection must be arranged with Mailouts (356-8593).
Turn Around Time:
2 days upon receipt at reference laboratory
Reference Range:
Negative
Interpretive Data:
A positive result indicates that Mycobacterium tuberculosis infection is likely. However, positive reactivity to proteins present in other mycobacteria such as Mycobacterium kansasii, Mycobacterium szulgai, and Mycobacterium marinum may cause false-positive results.

A positive QuantiFERON-TB Gold result should be followed by further medical and diagnostic evaluation for tuberculosis disease (eg, acid- fast bacilli smear and culture, chest x-ray).

QuantiFERON-TB Gold is usually negative in individuals vaccinated with Mycobacterium bovis Bacille Calmett-Guerin.
Comments:
Collection kit containing 3 tubes (NIL, Antigen, Mitogen) are the ONLY tube types validated.

Contact Core Laboratory at (356-3527) or Mailouts at (356-8593) for the THREE tubes (NIL, Antigen, Mitogen).

Cautions:
A positive QuantiFERON-TB Gold result may not indicate infection with Mycobacterium tuberculosis; false positives do occur.

A negative QuantiFERON-TB Gold result does not preclude the possibility of Mycobacterium tuberculosis infection or tuberculosis disease. Falsely-negative results can be due to the stage of infection (eg, specimen drawn prior to the development of cellular immune response), comorbid conditions that affect immune functions, or other individual immunological factors.

A false-negative QuantiFERON-TB Gold result can be caused by incorrect blood specimen drawn or improper handling of the specimen affecting lymphocyte function. Blood must be incubated with stimulation antigens within 16 hours of draw. Delay in incubation may cause false-negative or indeterminate results.

The effect of lymphocyte count on reliability is unknown. Lymphocyte counts may vary from person to person. The minimum number required for a reliable result has not been established.

QuantiFERON-TB Gold has been evaluated with specimens from patients with culture-confirmed active tuberculosis and from apparently healthy adults with and without identified risk factors for Mycobacterium tuberculosis infection.

The performance of QuantiFERON-TB Gold has not been evaluated in specimens from:
-Individuals with impaired or altered immune functions (HIV infections, transplant patients, those receiving immunosuppressive drugs such as corticosteroids) and those with other clinical conditions (eg, diabetes, hematological disorders)
-Individuals younger than 17 years old
-Pregnant women

Useful For: Indirect test for Mycobacterium tuberculosis complex infection (latent tuberculosis infection)
Methodology:
Enzyme-Linked Immunosorbent Assay (ELISA)
CPT Code:
86480