QFT accurately diagnoses Latent TB Infections (LTBI) which is an asymptomatic infection and is believed to affect over one-quarter of the global population. Approximately 5-15% of infected individuals will progress to active TBI if not diagnosed and treated. This progression is called the reactivation of LTBI.

QFT measures the amount of interferon gamma that is released when infected white blood cells in a blood sample come into contact with specific antigens of M. tuberculosis. The use of whole blood in QFT makes T cell incubation simple and fast, and reduces turn-around time (TAT). It is simple as there is no lymphocyte isolation, washing, counting, diluting, or culturing.

The QFT Test can be used be used for individuals who’ve had contact with individuals diagnosed with active pulmonary TB, are at increased risk of progression to active TB disease due to impaired immunity, have radiographic evidence of old, healed TB without history of treatment and have an increased risk for LTBI due to injection-drug use. Additionally, the following individuals should be screened for tuberculosis:

• Foreign-born persons and visitors from TB-endemic countries, especially immigrants who have arrived in the last two years
• Residents and employees of prisons and jails
• Individuals eligible for LTBI surveillance programs such as health-care workers, aid workers and military personnel

QFT works on patients who have previously been vaccinated against TB with the Bacille Calmette-Guerin (BCG) vaccination. QFT requires only one patient visit, has a low (1%) false-positive rate and high specificity (>99%) which reduces unnecessary evaluations (labs, X-rays).

The blood sample is collected in three specialized tubes (NIL, TB Antigen and Mitogen) that enable immediate exposure of the white blood cells to highly specific TB antigens. The QFT results are reported qualitatively as negative or positive for the bacteria, as well as quantitatively with a numerical value (reported in IU/mL). The numerical value indicates the amount of interferon gamma that is released when infected blood cells are exposed to specific antigens of M.tuberculosis.

For a test to be considered positive, the TB Antigen tube value minus the NIL tube value must be greater than or equal to 0.35 IU/mL.

QFT is a blood test that is collected in three sample tubes that allow for control-based testing in a laboratory environment. An immune response is observed when antigen from M. tuberculosis comes into contact with infected white blood cells. The test is simple, fast and considered the most clinically tested and proven. QFT can accurately diagnose LTBI, which is a state of persistent immune response which evidence of clinically active TB.

QFT is usually ordered to detect LTBI in the following conditions:  

• Individuals who’ve had contact with persons recently diagnosed with active TB
• Foreign-born persons and visitors from TB prone countries, especially immigrants who have arrived in the last two years
• People who are at increased risk of progression to active TB disease due to impaired immunity
• People with evidence of old, healed TB without history of treatment
• People with an increased risk for LTBI due to injection-drug use, and residents and employees of prisons and jails
• Persons who are, by history, at low risk for LTBI but whose future activity might place them at increased risk for exposure, and others eligible for LTBI surveillance programs (e.g., health-care workers, aid workers and military personnel)

The current fee for this test is C$95.00. It is not covered by the provincial health insurance plans, but it may be covered by extended health insurance plans.

The QFT test is available in select LifeLabs locations in Ontario; please refer to the table below for more details.

Barrie 480 Huronia, Suite 201
Belleville 210 Dundas St. E.
Brampton 36 Vodden, Suite 200
Brampton 9780 Bramalea Rd.
Brampton 40 Finchgate Blvd.
Burlington 3155 Harvester Rd.
Cambridge 697 Coronation Blvd.
Chatham 857 Grand Ave. W., Suite 106
Etobicoke 190 Sherway, Suite 108
Guelph 85 Norfolk St., Suite 101
Hamilton 25 Charlton Ave. E.
Hamilton 280 Queenston Rd.
Hamilton 989 Fennell Ave. E.
Ingersoll 45 King St. E.
Kingston 791 Princess, Unit 102
Kitchener 564 Belmont, Suite 105
London 746 Baseline Rd., Suite 101
London 1151 Richmond St.
Markham 379 Church St., Suite 111
Milton 470 Bronte Rd., Suite 106
Minden 6 McPherson St.
Mississauga 2300 Eglinton Ave., Suite G-04
Mississauga 101 The Queensway, Suite 138
Nepean 1 Centrepointe Dr.

North York 20 Wynford Dr., Unit 107
Newmarket 679 Davis Dr., Suite 123
North York 1333 Sheppard Ave. E.
North York 4949 Bathurst, Rm. 217
Oakville 1235 Trafalgar Rd.
Orleans 1220 Place d’Orleans Dr.
Oshawa 245 King St. W.
Ottawa 267 O’Connor St.
Ottawa 1919 Riverside Dr., Suite 105
Paris 238 Grand River St. N.
Peterborough 849 Alexander Crt., Suite 106
Picton 389 Main St.
Rexdale 115 Humber College Blvd.
Richmond Hill 250 Harding Blvd., Suite B03
Sarnia 429 Exmouth St., Suite 3
Scarborough 2330 Kennedy Rd., Suite 209
Sudbury 65 Larch St.
Thunder Bay 1040 Oliver Rd., Suite 101
Toronto 2 Champagne Dr., Unit C6
Toronto 340 College St., Suite 401
Thorold 3460 Schmon Pkwy,
Toronto 2221 Keele St., Unit 104, Toronto
Toronto 55 Queen St. E.
Windsor 6505 Tecumseh Rd. E.

Your doctor will receive the results between 5 to 10 business days of the blood test.

1. Qiagen, QuantiFERON®–TB Gold product information
2. Pai et. al. Canadian Tuberculosis Standards 7th Edition: 2014 – Diagnosis of latent Tuberculosis infection
3. Centers for Disease Control and Prevention, Guidelines for Using the QuantiFERON®-TB Test for Diagnosing Latent Mycobacterium tuberculosis Infection, 2012
4. CDC. Updated guidelines for using gamma release assays to detect m. tuberculosis infection. MMWR. 2010;59(RR05):1-25
5. City of Toronto, Tuberculosis Information for Healthcare Providers: Management of Latent Tuberculosis Infection and Active Disease – Information for Health Professionals
6. Latent tuberculosis infection: An overview – CCDR: Volume 43-3/4, March 2, 2017: Tuberculosis (TB)
7. World Health Organization’s Fact Sheet on Tuberculosis