TB skin testing (TST) is a useful tool for diagnosing inactive tuberculosis. The test is not as helpful in the diagnosis of active TB and can produce a ‘false negative’ result in some patients with advanced disease and/or who are immunocompromised. For more information about TB skin tests, please view the Middlesex-London Health Unit’s TB skin testing Information Sheet (PDF 69KB).
The skin test is administered intradermally using the Mantoux technique of tuberculin skin testing. Interpretation of a TST should be done between 48-72 hours of administration. More information about the proper administration of the TST can be found under TB Resources by clicking on the Canadian Tuberculosis Standards(8th ed) or the Tuberculosis Information for Health Care Providers (6th ed) guide.
Two Interferon Gamma Release Assays (IGRAs) are licensed for use in Canada: Quantiferon TB Gold and T-SPOT TB. Currently, these tests are not covered under the Ontario Health Insurance Plan (OHIP). Quantiferon TB Gold testing can be obtained on a limited basis through Gamma-Dynacare Medical Laboratories. The cost for this testing is approximately $90.00.
For current recommendations on the use of IGRAs, please refer to Chapter 4 in the Canadian Tuberculosis Standards.
For testing information on Quantiferon TB Gold, contact Dynacare 112-230 Victoria Street, London Ontario at (519) 432-1560.
