The indicator of active multiplication of Hepatitis B virus is:
**Core Concept**
The Hepatitis B virus (HBV) infection has different phases, including the immune tolerance phase, immune clearance phase, and inactive carrier phase. The indicator of active multiplication of HBV is crucial for determining the appropriate treatment and management strategy.
**Why the Correct Answer is Right**
The correct indicator of active multiplication of HBV is the presence of HBV DNA in the blood. This is because HBV DNA levels reflect the viral replication and multiplication. Elevated HBV DNA levels indicate active viral replication, which is a marker of disease activity and progression. The detection of HBV DNA is typically done using polymerase chain reaction (PCR) or other molecular assays.
**Why Each Wrong Option is Incorrect**
**Option A:** Elevated liver enzymes (e.g., ALT and AST) are not specific indicators of active HBV multiplication. While they may be elevated in HBV infection, they can also be elevated in other liver diseases, such as hepatitis C or non-alcoholic fatty liver disease.
**Option B:** Presence of HBsAg (hepatitis B surface antigen) is a marker of HBV infection, but it does not necessarily indicate active viral replication. HBsAg can be present in both active and inactive carriers.
**Option C:** Presence of anti-HBc (antibody to hepatitis B core antigen) is a marker of past or current HBV infection, but it does not indicate active viral replication.
**Clinical Pearl / High-Yield Fact**
HBV DNA levels are an important prognostic factor in HBV infection. Elevated HBV DNA levels (>20,000 IU/mL) are associated with a higher risk of liver fibrosis and cirrhosis.
**Correct Answer:** C. Presence of HBV DNA in the blood.