Synonyms

   HBsAg quant, qHBsAg

Clinical Significance

   Monitoring of progression of chronic hepatitis B in individuals who are confirmed to be positive for hepatitis B surface antigen. Monitoring of response to antiviral therapy in individuals who have chronic hepatitis B but are negative for hepatitis B e antigen and positive for hepatitis B e antibody.

Specimen

   Serum

Stability

   Refrigerated (preferred) : 7 days

   Frozen : 30 days

   Ambient : 7 days

Reference Range

   0.05 – 52000 IU/ml

Interpretation

   Result of < 0.005 IU/mL indicates that HBsAg is present in the serum specimen at a level below 0.005 IU/mL (the lower limit of quantification of this assay). Result of >150 IU/mL indicates that HBsAg is present in the serum specimen at a level above 150 IU/mL (the upper limit of quantification of this assay).

   In untreated hepatitis B e antigen (HBeAg)-positive patients, HBsAg levels of >100,000 IU/ml are associated with high replicative HBsAg carrier (immune tolerance). In untreated, HBeAg-negative patients, HBsAg levels of < 1000 IU/ml and hepatitis B virus DNA < 2000 IU/ml in serum or plasma are associated with lower risk for hepatocellular carcinoma, while HBsAg levels of < 100 IU/ml are associated with high rates of spontaneous HBsAg clearance.

Limitation

   Given the complex kinetics of hepatitis B virus (HBV) replication in chronic hepatitis B, a single undetectable result of hepatitis B surface antigen (HBsAg) in the serum specimen of an HBV-infected individual receiving antiviral therapy does not indicate cure or the absence of this virus in this individual. Serial measurements of HBsAg and other tests, such as HBV DNA (HBVQN / Hepatitis B Virus [HBV] DNA Detection and Quantification by Real-Time PCR, Serum) would be helpful or necessary to determine the definitive infection status in such individuals.

   Individuals, especially neonates and children, who recently received hepatitis B vaccination may have transient positive HBsAg test results because of the large dose of HBsAg used in the vaccine relative to the individual's body mass.