Update Type: Test Methodology Changed
Test Updated: 09/30/2021
Test Overview
Test Methodology

Chemiluminescent Immunoassay (CLIA)

Test Usage

Used to exclude TB infection in those individuals with a false positive TB skin test.

Reference Range *


* Reference ranges may change over time. Please refer to the original patient report when evaluating results.

Test Details
Days Set Up
within 2 weeks of receipt
Soft Order Code
MiChart Code
TB Gold, Quantiferon
  • QFTB
  • QuantiFERON-TB Gold Test
  • Mycobacterium tuberculosis, QuantiFERON-TB Gold
  • QFT
  • M. tuberculosis by QuantiFERON, B
  • Interferon (IFN)-gamma Release Assay
  • QuantiFERON-TB Gold In-Tube (QFT)
  • QNIL
  • QuantiFERON-TB Gold Plus Test
  • TB Gold-Plus
Chemical Pathology
Special Chemistry
Specimen Requirements
Collection Instructions

The TB Gold specimen collection kit includes four collection tubes - Nil (gray top), TB antigen 1(green top), TB Antigen 2 (yellow top) and Mitogen (purple top), a transport bag, and instructions for collection of the QuantiFERON samples. Collect 1 mL of blood into each of the four collection tubes; a black mark on the side of the tubes indicates the 1 mL fill volume (0.8 mL - 1.2 mL is acceptable for testing). Due to the low volume of draw, the vacuum in the tubes is minimal and the tube fills slowly; to ensure the correct volume is drawn, keep the tube on the needle for 2-3 seconds once the tube appears to have completed filling. The use of butterfly needles is discouraged. If a butterfly needle is used, utilize a waste tube to fill the butterfly line prior to filling the QuantiFERON tubes. Immediately after filling tubes, shake them ten (10) times just firmly enough to ensure the entire inner surface of the tube is coated with blood. Label each tube with the appropriate patient identifiers and collection time.
Process based on transport:
1. Transport at room temperature; do not refrigerate or freeze. Do not centrifuge the specimens. Specimens are accepted by the chemistry laboratory 24 hours a day, 7 days per week. Samples should be received in the lab within 8 hours of collection.

2. If specimen transport cannot be arranged for samples to arrive in the chemistry laboratory within 8 hours of collection, the specimens must be incubated as soon as possible and within 8 hours of collection. Incubate tubes upright at 37 degrees C for 16 to 24 hours (DO NOT use a heating block for incubation). Label tubes as "incubated", refrigerate and send to MLabs within 3 days.

Special Handling

Requires TB Gold specimen collection kit.

Rejection Criteria
Overfilled or underfilled tubes
Incubation performed in a heating block
CPT Code
Fee Code