QuantiFERON-TB Gold Plus, 1 Tube

Quest Diagnostics

Sample type: Whole blood

Requires fasting: No

Phlebotomy required

Details

QuantiFERON®-TB Gold Plus, 1 Tube - This test is a blood-based interferon-gamma release assay (IGRA) used as an aid in the diagnosis of Mycobacterium tuberculosis infection. It is an immune response-based, indirect test for M tuberculosis infection (including disease) and is intended for use in conjunction with risk assessment, radiography, and other medical and diagnostic evaluations. Additional testing is needed to determine if a person who has tested positive has latent tuberculosis (TB) infection or TB disease.

Biomarker summary

Mitogen-NiL
NiL
TB1-NiL
TB2-NiL
QuantiFERON-TB Gold Plus, 1 Tube

Additional details

Estimated days for results: Results should be available in 2 - 5 business days after the sample is collected

Details

This in vitro diagnostic test uses a peptide cocktail simulating ESAT-6, CFP-10, and TB7.7 proteins to stimulate cells in heparinized whole blood. Detection of interferon-γ (IFN-γ) by ELISA is used to identify in vitro responses to those peptide antigens that are associated with Mycobacterium tuberculosis infection.

For the four-tube QFT-Plus testing option, see test code #36971.

Guidelines recommend testing for individuals who 1) have been exposed to a person with latent or active TB, including the general population and healthcare workers; 2) are from TB-endemic countries, which include most countries in Latin America, the Caribbean, Africa, Asia, and Eastern Europe, and Russia; 3) work in high-risk settings, such as correctional facilities, long-term care (LTC) facilities, nursing homes, and homeless shelters; or 4) have HIV or have an injection drug substance use disorder [1].

All of these individuals can be tested with either a traditional tuberculin skin test (TST) or an IGRA. However, the American Thoracic Society (ATS), the Infectious Disease Society of America (IDSA), and the Centers for Disease Control and Prevention (CDC) jointly prefer an IGRA test for individuals who have been vaccinated against bacillus Calmette-Guérin (BCG) or are not likely to return for the follow-up portion of the TST (and in both cases are at least 5 years old and likely to have TB infection and are at low or moderate risk of disease progression, or in whom it has been determined that TB testing is necessary)[1].

The QuantiFERON-TB Gold test has specificity >99% in low-risk individuals and sensitivity of 92% in individuals with active disease [2].

In contrast to the TST, IGRA testing for TB requires only 1 patient visit (instead of 2). Also, IGRAs are not associated with the booster phenomenon, in which previously infected individuals generate a false-positive on a TST. In addition, prior BCG vaccination does not generate a false-positive result. Note that for children aged 2 and above, either TST or IGRA can be used [3,4].

The CDC does not recommend dual testing with both a TST and an IGRA, unless the goal is to confirm a positive result, or when a high-risk individual’s test results are negative and there is clinical suspicion of TB. In this clinical situation, dual testing is used for confirmatory purposes [4].

Note that when using QuantiFERON®-TB Gold Plus, blood samples must be processed within 16 to 48 hours after collection while white blood cells are still viable.

References
1. Lewinsohn DM, et al. Clin Inf Dis. 2017;64:111-115.
2. QuantiFERON®-TB Gold Elisa [package insert]. Germantown, MD: Qiagen; August 2016.
3. American Academy of Pediatrics. In: Kimberlin DW, et al, eds. Red Book: 2018 Report of the Committee on Infectious Diseases, 31st ed. Itasca, IL: American Academy of Pediatrics;2018: 829-853.
4. CDC. Fast facts: Interferon-gamma release assays (IGRAs)-blood tests for TB infection. Published November 2011. https://www.cdc.gov/tb/publications/factsheets/testing/igra.htm

What type of sample is required for this test?

6 mL whole blood collected in a no gel lithium heparin (green-top) tube

Test Resources

For more information, please consult your healthcare provider.

Average sample processing time

2–5 business days

Reference range

Negative

Health categories

Infectious Disease

Patient instructions

Blood Draw Options with Fullscript
Fullscript offers several convenient phlebotomy options to complete your lab testing:

Quest Diagnostics Patient Service Centers (PSC)

Location: Visit a nearby Quest Diagnostics Patient Service Center.
Cost: $10 sample collection fee (paid during lab order checkout).
Scheduling: Schedule your appointment here. Appointments are recommended to reduce wait times. Walk-ins are accepted, but may experience delays. Aim to arrive 10 minutes before your appointment.
Collection Instructions:

Bring a valid ID.
Bring your digital or printed requisition form, available in the Labs tab of your Fullscript account.

Check-in: Scan the QR code from your confirmation email or follow kiosk instructions.
More Info: Quest Diagnostics blood draw guide

Getlabs Mobile Phlebotomy

Location: Sample collection at your home or office.
Cost: $85 sample collection fee (paid during lab order checkout).
Availability: Available in most locations – enter your ZIP code during checkout to confirm.
Scheduling: Schedule your appointment here through your Fullscript account.
Collection Instructions:

Have your digital or printed requisition form and valid ID ready.
Your phlebotomist will contact you by phone to coordinate arrival.

More Info: Getlabs blood draw guide

In-office phlebotomy instructions

Specimen

Preferred Specimen(s): 6 mL whole blood collected in a no gel lithium heparin (green-top) tube
Alternative: NA
Minimum Volume: 6 mL
Collection Instructions: NA

Storage and shipping instructions