Laboratory Services

QuantiFERON-TB Gold Plus, Blood

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Updated Test Information:

Test Description
QuantiFERON-TB Gold Plus, Blood

IGRA-TB, interferon gamma release assay to tuberculosis antigens, QFT, Quantafluor TB, Quantiferon TB-gold, Quantiferon TB-gold Plus, UOW3622

Test ID
General Information

This test is for the diagnosis of latent TB (tuberculosis) infection, but not of active TB disease which requires AFB culture and smear (See AFBHSC).

Specimen Collection / Processing Instructions

Option 1" QuantiFERON®-TB Gold PLUS (4 tube assay). Collect 1 mL blood in each tube: [one NIL (Grey top), one TB1 Ag (Green top), one TB2 Ag (Yellow top), one MIT (Lavender top)]. The black mark on the side of tubes indicates the 1 mL fill volume. Do not under or over-fill. Immediately after filling tubes, shake all four tubes 10 times to ensure that the entire inner surface of the tube has been coated with the blood.

Tube Labeling Note: Please ONLY use SMALL LABELS and affix on tubes towards the top half so that there is a clear view of both the amount of blood in the tube and the manufacturer lot #.

Option 2: Draw blood into a lithium-heparin tube. Fill a lithium-heparin blood collection tube (minimum volume 5 ml) and gently mix by inverting the tube several times to dissolve the heparin.   Transport the lithium-heparin tube to the laboratory at 2–8°C.   Blood drawn into a lithium-heparin tube may be refrigerated up to 48 hours.  DO NOT USE Lithium-heparin PST (plasma separator tube) for collection.

Minimum Sample Volume

1 mL blood/each tube +/- 0.2 ml blood

Additional Processing Details

Specimen must be incubated within 16 hours of blood draw. Specimen must arrive at Virology lab within this window.

For Monday-Friday Blood Draws: Collect sample before 18:00 and ship to Virology same day. If blood is drawn after 18:00, HOLD at Room Temperature and ship to Virology next day so that it arrives by 08:00 the next morning.

For Saturday-Sunday Blood Draws: Collect sample before 1500 and ship to Virology same day. If blood is drawn between 15:00-19:00 call Virology lab at 206-685-8037 to see if someone is available to receive sample. If no answer, DO NOT leave a message. Recollect sample after 19:00 and HOLD at Room Temperature and ship to Virology next day so that it arrives by 10:00.

UW Virology Lab is open Monday-Friday 07:00-21:00 and weekends/Holidays 08:00-17:00. If unable to contact Virology and uncertain how to proceed, call Lab Medicine Resident at 206-598-6190.

Note: Quantiferon TB collections tubes are available in Lab Medicine's Specimen Processing, at UW-MT call 206- 598-6224 or at HMC call 206-744-3451. Store blood collection tubes at 4°C to 25°C

Department (code)

Clinical Virology (CVIR)

CPT Code(s)


Performing Lab

UW Laboratory

LOINC Code(s)
Additional Information

QuantiFERON®-TB Gold PLUS (4 tube assay).

Confirm volume in all 4 tubes (Grey top NIL tube, Green top TB1 ANTIGEN tube, Yellow top TB2 ANTIGEN tube and Purple top MITOGEN tube) is at or near the black fill mark. The black mark on the side of the tubes indicates the 1.0 ml fill volume. The blood collection tubes have been validated for volumes ranging from 0.8 to 1.2 mls. If the level of the blood is not close to the indicator line. Reject sample and request a redraw. Use SMALL CID labels ONLY and place near the top of the tube. NOTE: Do NOT cover up blood volume level or lot number of tube with labels!

Store blood collection tubes at 4°C to 25°C. All tubes must be incubated within 16 hours of collection. 

Alternatively, outside labs may place all 4 tubes upright in a 37°C +/- 1°C incubator for 16-24 hours on site. After incubation, mark the tubes as "INCUBATED". Blood collection tubes may be held at 4-27°C for up to 3 days after incubation and prior to centrifugation. Centrifuge incubated tubes at 2000 to 3000 RCF (g) and store 2-8°C. Centrifuged tubes may be held at 2-8°C for up to 28 days. Document incubation time and temperature on the requisition. Ship centrifuged tubes on wet ice.