Hepatitis B - DNA Viral Load

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Testing Indications

Hepatitis B Virus (HBV) DNA testing should not be used as a diagnostic test for hepatitis B infection and should only be ordered in those with a confirmed HBV infection based on serologic testing. Current clinical guidelines recommend that patients infected with hepatitis B should have their HBV DNA level measured at baseline (i.e., prior to starting therapy) and at three to six month intervals while receiving antiviral therapy. More frequent testing may be indicated for those patients suspected of having developed resistance to their antiviral therapy. Although there may be other clinical indications for requesting an HBV DNA test (e.g. a patient in whom the only marker of infection is a positive HBcAb test), routine monitoring of HBV-infected patients who are not on treatment or being considered for treatment is not recommended.

Specimen Collection and Handling

Specimen Requirements

Test Requested	Required Requisition(s)	Specimen Type	Minimum Volume	Collection Kit
HBV DNA	HCV/HBV Viral Load, Genotyping, and Drug Resistance Testing Requisition	Serum¹	2.5 ml	Blood, clotted - vacutainer tubes (SST)
HBV DNA	HCV/HBV Viral Load, Genotyping, and Drug Resistance Testing Requisition	Whole Blood²	5 mL	SST or any tubes without additive²

Submission and Collection Notes

Freshly drawn whole blood specimens (SST) may be stored and/or transported at 2°C to 25°C for up to 24 hours before centrifugation. Following centrifugation, remove serum from cells immediately, and transfer serum into screw-capped cryovial tubes.. Serum specimens may be stored and/or transported at 2°C to 8°C for up to 6 days or at ≤-18°C for up to 12 weeks. If more extended storage of serum specimens is required, it must be frozen at ≤-60°C.

Unspun whole blood must be received at Public Health Ontario’s (PHO) Laboratory within 24 hours of collection before 2:00 p.m. Monday – Friday.

Limitations

Grossly haemolysed, icteric, lipemic or microbially contaminated serum is not recommended for testing.

Storage and Transport

Label the specimen container with the patient’s full name, date of collection and one other unique identifier such as the patient’s date of birth or Health Card Number. Failure to provide this information may result in rejection or testing delay.

Place specimen in a biohazard bag and seal. It is recommended to ship specimens for testing to PHO Laboratory immediately after collection or processing to avoid delays in testing.

Shipping of specimens shall be done by Transportation of Dangerous Goods (TDG) certified individuals in accordance with TDG regulations.

Requisitions and Kit Ordering

Test Frequency and Turnaround Time (TAT)

Hepatitis B DNA viral load testing is performed daily Monday to Friday.

Turnaround time is up to 8 business days from receipt by PHO Laboratory.

Test Methods

Specimens for HBV DNA viral load are tested using the Roche cobas® HBV Quantitative Assay on the cobas® 6800/8800 system. The cobas® HBV assay is an in vitro nucleic acid amplification test for the quantitation of HBV DNA in serum of HBV-infected individuals.

Interpretation

Results should be interpreted in the context of the patient’s clinical presentation, risk factors, and exposure history. The table below is a guide for the interpretation of HBV DNA viral load results.

Results	Interpretation
Not detected	HBV DNA not detected
<1.00E+01 IU/mL	HBV DNA detected below the lower limit of quantitation. Unable to quantify. (An exact value for HBV viral load cannot be calculated as it is below the lower limit of quantitation of 10 IU/mL.)
1.00E+01 to 1.00E+09 IU/mL	Viral load will be reported in IU/mL.
>1.00E+09 IU/mL	HBV DNA detected above the upper limit of quantitation. Unable to quantify. (An exact value for HBV viral load cannot be calculated as it is above the upper limit of quantitation of 1.0E+09 IU/mL.)