Hepatitis B Decision Tool – Initial Screening

Hepatitis B Decision Tool - Initial Screening
Summary: A Hepatitis B decision tool for interpretation of initial screening tests.
See soapnote's Hepatitis B Screening Decision Tool [link url="https://www.soapnote.org/infectious/hepatitis-b-screening" memo="here"] and Hepatitis B Chronic Decision Tool [link url="https://www.soapnote.org/infectious/hepatitis-b-chronic" memo="here"]
[select name="Q1" value="negative|positive"] <-- HBsAg - Hepatitis B surface antigen
[select name="Q2" value="negative|positive"] <-- HBsAb - Hepatitis B surface antibody
[select name="Q3" value="negative|positive"] <-- HBcAb - Hepatitis B core antibody
[conditional field="Q1|Q2|Q3" condition="(Q1).is('negative')&&(Q2).is('negative')&&(Q3).is('negative')"]Susceptible to HBV infection
Interpretation - Susceptible to Hepatitis B infection.
Recommendation - Vaccination.  [/conditional][conditional field="Q1|Q2|Q3" condition="(Q1).is('negative')&&(Q2).is('positive')&&(Q3).is('negative')"]Immune to HBV infection (vaccinated)
Interpretation - Immune to Hepatitis B infection due to vaccination. 
Recommendation - No intervention required.  [/conditional][conditional field="Q1|Q2|Q3" condition="(Q1).is('negative')&&(Q2).is('positive')&&(Q3).is('positive')"]Immune to HBV infection (resolved natural infection)
Interpretation - Immune to Hepatitis B infection due to natural infection. 
Recommendation - No intervention required.  [/conditional][conditional field="Q1|Q2|Q3" condition="(Q1).is('positive')&&(Q2).is('negative')&&(Q3).is('positive')"]Acute or chronic HBV infection
Interpretation - Acute or chronic Hepatitis B infection. 
Recommendation -
Obtain Hepatitis B IgM to clarify whether acute (positive IgM) or chronic (negative IgM).  [/conditional][conditional field="Q1|Q2" condition="(Q1).is('positive')&&(Q2).is('positive')"]This isn't an ordinary finding.  Hepatitis B surface antigen and Hepatitis B surface antibody shouldn't both be positive.  [/conditional][conditional field="Q1|Q2|Q3" condition="(Q1).is('negative')&&(Q2).is('negative')&&(Q3).is('positive')"]Interpretation unclear
Interpretation - Unclear; four possibilities:
1.  Resolved infection (most common)
2.  False-positive anti-HBc, thus susceptible
3.  "Low level" chronic infection
4.  Resolving acute infection
Recommendation - 
To evaluate for possible low level chronic hepatitis infection, obtain quantitative Hepatitis B DNA level, serum ALT, and Hepatitis B e antigen and antibody.  
To detect possible acute infection in window phase, obtain Hepatitis B core antibody IgM level (positive in acute disease).[/conditional][conditional field="Q1|Q2|Q3" condition="(Q1).is('positive')&&(Q2).is('negative')&&(Q3).is('negative')"]Unusual and transient finding.  
Interpretation - Unclear; two possibilities:
1.  Early acute infection
2.  Transient finding up to 18 days after vaccination
Recommendation - Clinical judgement can guide further investigation, such as short interval retesting.[/conditional]
You may wish to proceed to evaluation and treatment of Chronic Hepatitis B.  This is located at https://www.soapnote.org/infectious/hepatitis-b-chronic [link url="https://www.soapnote.org/infectious/hepatitis-b-chronic" memo="(link)"]

[checkbox memo="display/hide references" name="footnotes" value=""][conditional field="footnotes" condition="(footnotes).is('')"]
references:  
 AFP article on diagnosis and treatment of hepatitis B - Wilkins (2010) Am Fam Phys 81: 965-72: [link url="//www.aafp.org/afp/2010/0415/p965.html" memo="#1"]
 CDC Hepatitis B page [link url="//www.cdc.gov/hepatitis/HBV/index.htm" memo="#2"]
 CDC serology chart [link url="//www.cdc.gov/hepatitis/HBV/PDFs/SerologicChartv8.pdf" memo="#3"]
 American Association for Study of Liver Diseases (AASLD) - Hepatitis B Guidelines [link url="//www.aasld.org/practiceguidelines/Pages/default.aspx" memo="#4"][/conditional]