QuantiFERON - TB Gold Plus (QTF4) Assay QFT4

Method(s) Chemiluminescence immunoassay
Specimen Required
Collect

Monday – Thursday (Do not collect on weekend or before holidays)

(Note - Physician clients in the local Syracuse area are encouraged NOT to collect this test in their office. Please send the order and patient(s) to one of the Lab Alliance Patient Service Centers.)

Transport

Four special blood collection tubes are needed per patient. Immediately after blood collection shake them 10 times just firmly enough to ensure the entire inner surface of the tube is coated with blood. Over-energetic shaking may cause gel disruption and could lead to aberrant results. All four tubes MUST be submitted for testing.

Unacceptable Conditions

Blood samples received longer than 15 hours after specimen collection; specimens refrigerated or exposed to excessive heat, over- or under-filled tubes; submission in any tubes other than 4 collection tubes.

Billing Code 1010590
CPTCode 86480
Preferred Specimen Collection Device(s)
Reference Interval


 
Components Reference Interval
QuantiFERON-TB1 minus NIL0.34 IU/mL or less
QuantiFERON-TB2 minus NIL0.34 IU/mL or less

Interpretation

Positive: IFN-y response to Mycobacterium tuberculosis antigens, suggesting infection
with M. tuberculosis. For patients at low risk for infection, a second test or repeat test
should be considered. Prior infection with M. kansasii, M. szulgai and M. marinum may lead to false positive results

Negative: No IFN-y response to Mycobacterium tuberculosis antigens and infection with M. tuberculosis is unlikely. For patients at high risk for infection, a second test should be considered.

Indeterminate: Indeterminate results can result from either a poor response to positive control mitogen, which may be secondary to low lymphocyte count, decreased lymphocyte activity or immunosuppression, or from a high background (nil) response, which may be secondary to heterophile antibody effects or circulating IFN-y in the patient's blood.

No Appointment Necessary
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11 Patient Service Centers in Central New York.

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