Hepatitis B virus DNA (viral load)

What it measures

Quantifies HBV genomes in blood by nucleic acid amplification. It guides treatment decisions, monitors antiviral response and detects occult infection.

Specimen and preparation

• Specimen: EDTA plasma or serum
• Tube: Lavender top
• Preparation: Separate plasma within 6 hours; freeze if delayed.

Reference range

Reference ranges differ between laboratories, methods and populations. Always use the range printed on your own lab report.

Causes of high values

• Active replication in chronic hepatitis B
• Treatment failure or antiviral resistance
• Reactivation during immunosuppression
• High transmission risk in pregnancy (> 200,000 IU/mL)

Causes of low values

• Effective antiviral therapy
• Inactive carrier (usually < 2,000 IU/mL)

Method

Real-time PCR (quantitative)

Good to know

Report in IU/mL; a rise of more than 1 log above nadir on therapy suggests resistance.

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