Hepatitis B Surface Antigen General Clinical Tests
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| Test Name
Method |
Hepatitis B Surface Antigen, Total Anti- HBs, HBsAg
|
| Specimen
Requirements |
Serum
Stable for 7 d at RT and indefinitely at 4° C or – 20°C. |
| Ref. Range
Conventional International Recommended Units |
Negative
Limits of detection: 0.02-1.0 ng/mL; Typical positive quantitation 10(4)-10(5) ng/mL |
| Chemical Interfaces
In Vivo Effects |
None Found;
|
| Diagnostic Information | HBsAg is the surface lipoprotein coat of the Hepatitis B virus. It was originally discovered by Blumberg and was called Australian anitgen. Hepatitis B is a retrovirus of the Hepadnavirdae family that can cause persistent infection leading to cirrhosis and hepatocellular carcinoma. It has a unique partially double-stranded circular DNA which utilizes the same nucleotide sequences to code for different proteins by frame-shifting. The virus infects hepatocytes, which then produce complete viral particles as well as excess HBsAg. The Hepatitis B virus is not cytopathic. Instead, the host immune reaction to foreign viral proteins lyses infected hepatocytes and causes hepatitis. Because of immature host immunity, infected neonates and young children are much more likely to become chronic carriers of the Hepatitis B than adults. HBsAg compromises three proteins, (SHBs, encoded by the S domain of the Hepatitis B genome; MHBs, encoded by S+preS1; and LHBs, encoded by by S+preS1+preS2). Detection of HBsAg is usually the first detectable marker of Hepatitis B infection and remains positive in persistent infections. Therefore, HBsAg should be tested in the clinical settings of both acute and chronic patients. |
| Remarks | HBsAg produced by recombinant DNA techniques in yeast is used as a highly effective vaccine. Original vaccines used purified HBsAg harvested from chronic Hepatitis B carriers.Quantitation of HBsAg is possible but not usually performed. With acute Hepatitis B a 50% drop in HBsAg serum concentrations after one month indicates resolving infection, whereas an increase implies persistence.A number of reports have documented chronic Hepatitis B infections without HBsAg detectable in serum. Although this is rare, the presence of the virus can be deduced by testing for anti-HBc, anti-HBs, and HBV-DNA. |
References:
Clinical Guide to Laboratory Tests, third edition.
