HEPATITIS B SEROLOGY
INTERPRETING HEPATITIS B SEROLOGY
- Hepatitis B serology is generally accepted to be more complex and more difficult to interpret than hepatitis C serology. The aim of hepatitis B testing is to establish whether the hepatitis B virus is present, whether the person has immunity to the virus from either a previous infection or hepatitis B vaccination, or whether the person may be susceptible to the virus.
- As with hepatitis C, the sample for determining a person’s hepatitis B status can be obtained reliably through whole blood venipuncture or through less invasive dried blood spot. Only one sample of blood is needed for a hepatitis B blood test.
COMBINATION OF TESTS
There is more than one test for hepatitis B. Screening and determining the immune status of people at risk of chronic hepatitis B infection is done by detecting several markers and a combination of test results are needed to fully understand if a person is infected or not and to determine the appropriate management:
+Hepatitis B surface antigen (HBsAg)
Hepatitis B surface antigen (HBsAg) is a protein on the surface of the virus. HBsAg can be detected in high levels in the blood during acute or chronic hepatitis B infection. A ‘positive’ or ‘reactive’ test result means the person has a current hepatitis B infection, which may either be acute or chronic.
+Hepatitis B surface antigen-specific antibody (HBsAb or anti-HBs).
A ‘positive’ or ‘reactive’ HBsAb test result indicates the person has immunity to the virus. Immunity can develop either through successfully recovering from previous hepatitis B infection or through being protected successfully by the hepatitis B vaccine.
+Hepatitis B core antibody (HBcAb or anti-HBc)
Hepatitis B core antibody (HBcAb or anti-HBc) can be detected and is a marker for infection. A ‘positive’ or ‘reactive’ HBcAb test result indicates previous or ongoing infection.
+ Additional Blood Tests
Hepatitis B can be a complicated liver infection to understand, so additional blood tests, including further hepatitis B markers and Liver Function Tests (LFTs) may be required to get a better understanding of what kind of care and follow-up might be needed.
Some clinical guidelines recommend that all people who test positive for HBsAg, and especially people with any signs of advanced fibrosis or cirrhosis, or pregnant women are referred to specialist treatment for a more comprehensive assessment.
However, many people with chronic hepatitis B infection may only antibodies for the hepatitis B infection from previous exposure and therefore may not require referral to a specialist and can be well supported and monitored by their general practitioner. It is therefore essential under these circumstances that general practitioners and other non-specialist medical health providers understand the clinical course of chronic infection, which may change over time as a result of the relative balance between viral replication and the person’s immune response to the infection.
Without specialist care, people with hepatitis B should be monitored at least once a year for any changes in liver health.