Hepatitis B Virus DNA Quantitative Test

When a patient's hepatitis B virus (HBV) DNA level is <100 IU/mL, it means that the virus is present at the lower limit of detection of standard tests. With most conventional assays, the virus cannot be detected if it's below 100 IU/mL. This situation may occur in individuals who have not undergone antiviral therapy and may indicate a "small three positive" status, which refers to a specific pattern in hepatitis B antigen/antibody testing.

It is also common in patients who have responded well to antiviral treatment, where the viral load has dropped below 100 IU/mL. In such cases, it is highly recommended to undergo a high-sensitivity HBV DNA test, which can detect levels as low as 15 or 20 IU/mL. If the virus remains undetectable at these lower thresholds, it indicates a successful response to treatment and effective viral suppression.

If a high-sensitivity test returns results between 15-100 IU/mL, this suggests low-level viral replication. These patients may require adjustments to their antiviral regimen to further suppress the virus and reduce the risk of liver damage over time.

For individuals with small three positive status who have not yet started antiviral therapy, a viral load <100 IU/mL typically indicates minimal viral activity. If liver function is normal, there is no family history of cirrhosis or liver cancer, and imaging tests such as liver ultrasound and fibroscan show no significant fibrosis, these individuals are often classified as "healthy HBsAg carriers." At this stage, antiviral treatment is generally not required, but regular monitoring is essential.

It is important to note that HBV DNA levels can change over time. A person who appears to be a healthy carrier today may experience a reactivation of viral replication within months or years. Therefore, ongoing follow-up is crucial to reassess the need for treatment based on any changes in viral activity or liver health.