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Hepatitis B Viral Load Testing

Hepatitis B Viral Load Testing

As of August 12, 2013, the Diagnostic Virology and Reference Laboratory will be changing the test system for hepatitis B viral load.
The current system, the Abbott Real Time HBV, will be replaced by the Roche Diagnostics Cobas Ampliprep/Cobas Taqman HBV, version 2.0. Both tests are real-time PCR based and the literature and our own evaluation demonstrate equivalent performance in measuring HBV viral loads. The dynamic range of the Roche system (the range within which accurate quantification can be achieved) is 20 IU/mL to 1.7x108 IU/mL (Abbott dynamic range is 10 IU/mL to 1.0x109IU/mL). Our current reporting of results includes both Copies per mL as well as International Units per mL (IU/mL). Because the new Roche test results in somewhat different Copies per mL than the Abbott system, we will only be reporting International Units per mL with the Roche test, so as to avoid confusion around possible changes in Copy number unrelated to patient determinants. The translation to International Units normalizes the viral load to an international standard so that results from different assays can be compared for patient management purposes. We will be including the conversion factor from Copies to International Units in the results section for those who may wish to calculate the Copy number.
For any enquiries about this change please contact Dr. Chris Sherlock at (604) 806-8422 or the Providence Health Care Medical Microbiologist on call through the PHC switchboard.