LATENT TB INFECTION

Synonyms: Quantiferon; Interferon Gamma Release Assay; IGRA, QFT, LTBI
Computer Code: (LTBI)
Specimen Collection: Only collection tubes supplied by the Microbiology laboratory are to be used for this test. All 4 tubes in the collection kit must be filled with blood. One ml of blood drawn (up to fill line) into each tube. Additional points to keep in mind: 1. Tubes have a fill line, but blood drawn can vary by 0.2 ml. Hence, the acceptable blood drawn range is from 0.8 to 1.2 ml. 2. If butterfly needle used, then a purge tube should be used to eliminate the air in the line so proper volume can be drawn into the QFT tube. 3. Preferably, Collect the tubes in the order of grey top, green top, yellow top , and then purple top. 4. Once drawn, mix tubes up and down 5 seconds or 10 times just firmly enough to ensure the entire surface of the tube has been coated with blood. (Do not shake vigorously).
Minimum Volume: 4 x 1mL The black marks on the side of the tube indicate the 1ml fill volume. If Butterfly needle used a red discard tube should be used to purge the extra air in the tubing.
Handling Instructions for Offsite Areas: Specimen must be in the lab within 16 hours of being drawn. Transport specimen at room temperature.
Reference Values: Negative
Lab Code: MIC
Requisition: SPEC M
Test Frequency: 2/week
Routine TAT: 1-8 days
Stat TAT: N/A
CPT Code(s): 86480
LCD or NCD:
Methodology Used:
See Addendum XVII