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Test Code QTBG Quantiferon-TB Gold Plus

Infectious

Specimen and Container/Tube

Specimen Type: Whole blood

Preferred Specimen: QuantiFERON®-TB Gold Plus (QFT®-Plus) Blood Collection Tubes:

  • QuantiFERON Nil Tube (gray cap with white ring)
  • QuantiFERON TB1 Tube (green cap with white ring)
  • QuantiFERON TB2 Tube (yellow cap with white ring)
  • QuantiFERON Mitogen Tube (purple cap with white ring)

Volume

Minimum Volume: 1 mL per tube

 

Specimen Stability

Storage Temperature

Stability

Room temperature

(22 - 27°C)

 8 hours

Refrigerated

(2 - 8°C)

 not acceptable

Frozen

(-20°C)

not acceptable

Collection Instructions

Specimen Collection: 

1. Collect 1 mL of blood by venipuncture directly into each of the QFT-Plus Blood Collection Tubes.

2. Tube may fill slowly. Hold tube for 2-3 seconds after flow ceases.

3. If a “butterfly needle” is being used to collect blood, a “purge” tube should be used to ensure that the tubing is filled with blood prior to the QFT-Plus Collection Tubes used.

4. Immediately after filling the tubes, shake them ten (10) times enough to make sure the entire inner surface of the tube is coated with blood.

5. Store at room temperature. DO NOT refrigerate.

6. Send to Laboratory Service Center as soon as possible.

 

Specimen Transport: Immediate

Specimen Handling and Transport Instructions

UCMC Onsite Instructions: Collect specimen per standard collection procedure and send to laboratory immediately. 

 

UCMC Offsite and UC MedLab Outreach Instructions: Collect specimen per standard collection procedure and send to laboratory immediately.

Rejection Criteria

  • Common specimen rejected situations include: incorrect specimen type, insufficient volume, incorrect collection container, missing or incomplete specimen identifiers, incorrect specimen transport, or specimens outside stability limits. 

Reference Values

 

Test

Age

Sex

Reference Range

Negative

All

All

 M. tuberculosis infection NOT likely

Turnaround Time

Turnaround times are relative to the time the specimen is received in the test laboratory. 

STAT Turnaround Time: not available

Routine Turnaround Time: 3 days

Testing Schedule: Monday - Sunday

Clinical Indications

  • Used to identify in vitro responses to peptide antigens that are associated with Mycobacterium tuberculosis infection
  • This test is not recommended for use for diagnosis of active tuberculosis infection

Methodology

Enzyme-linked immunosorbent assay (ELISA)

CPT Codes

86480

LOINC Codes

71775-1

Synonyms/Keyword Search

QFT, QUANTIFERON, TB, Mycobacterium tuberculosis, Latent Tuberculosis, Interferon-gamma

Last Review Date

06/12/2026