October 17, 2010

Q&A: Complications of Hepatitis B Virus Infection

The identification of hepatitis B virus (HBV) infection was revolutionized by the discovery of Australia antigen, now called hepatitis B surface antigen (HBsAg). During the ensuing two decades, serologic assays were established for HBsAg and other HBV antigens and antibodies. Advances in molecular biology techniques led to the development of hybridization and polymerase chain reaction (PCR) assays for direct determination of hepatitis B virus DNA (HBV DNA). The diagnosis of HBV infection can also be made by the detection of HBsAg or hepatitis B core antigen (HBcAg) in liver tissues by immunohistochemical staining and of HBV DNA by Southern hybridization, in-situ hybridization, or PCR.

This article is for Medical Students & Professionals
This is a Question & Answer revision article designed for medical students and professionals preparing for the PLAB, MRCP or USMLE examinations. They are based on actual questions from these examinations. You may find the Hepatitis B Infection article more useful, or one of our many articles on Diseases & Conditions, Medical Syndromes, Health & Wellness or Home Remedies.
In this article:
Who should be tested for hepatitis B?
MCQ: clinical scenario
MCQ: answer
MCQ: explanation

Who should be tested for hepatitis B?

Testing for hepatitis B virus (HBV) is indicated for:
  • Those with signs and symptoms of acute or chronic hepatitis.
  • Asymptomatic patients who are at high risk for having been exposed to HBV or are at risk for severe adverse outcomes from undiagnosed infection.
It is estimated that approximately two billion people worldwide have evidence of past or present infection with HBV, and 257 million individuals are chronic carriers.

MCQ: clinical scenario

A young man develops acute hepatitis B. Four months after his presentation he asks for a test that would predict the likelihood of developing long term disease.

Which agent would be most helpful in estimating the likelihood of developing chronic active hepatitis in this patient?

a) recombinant hepatitis B vaccine
b) hepatitis C virus
c) hepatitis B surface antigen
d) hepatitis B immune globulin (HBIG)
e) hepatitis B virus DNA
f) hepatitis B e antigen

MCQ questions & answers on medicalnotes.info

MCQ: answer

The correct answer is F

MCQ: explanation

Hepatitis B e antigen (HBeAg) is a product of the gene that codes for the nucleocapsid core; its presence signifies the presence of a state of high virus replication. As such, patients with HBeAg have a high level of circulating virions, high infectivity, and substantial liver injury. HBeAg becomes detectable in all patients early during acute hepatitis B, and, therefore, there is no clinical utility to the test during early acute hepatitis B; however, if circulating HBeAg persists beyond the first 3 months of acute hepatitis, the likelihood of chronic infection is increased.

Testing for HBeAg is more important during chronic infection, for the presence of HBeAg denotes a more highly replicative chronic infection, associated with increased infectivity (eg, 20-25% infectivity of a needlestick) and liver injury (eg, chronic active hepatitis). When anti-HBe can be detected in the absence of HBeAg during chronic infection, the patient can be classified as having a less replicative infection, with limited infectivity (eg, 0.1% infectivity of a needlestick) and liver injury (chronic carrier).

Hepatitis B virus DNA (HBV DNA) is a more quantitative marker of HBV replication, and is helpful in following patients with chronic disease and in monitoring the success of antiviral therapy.

Reference(s)
1). UpToDate: Hepatitis B virus: Screening and diagnosis. Available online: https://www.uptodate.com/contents/hepatitis-b-virus-screening-and-diagnosis

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