Critical Care Medicine-Infections and Immunologic Disease>>>>>Gastrointestinal and Intra-abdominal Infections
Question 1#

A 38-year-old man who recently returned from visiting his family in the Philippines presents to the emergency department with 1 week of fatigue, low-grade fever, abdominal pain, and jaundice. Laboratory results include:

• serum alanine transaminase (ALT) 2,850 U/L
• total bilirubin 7.6 mg/dL
• international normalized ratio (INR) of 3.6

Serology comes back as:

• HBsAg negative
• anti-HBs positive
• anti-HBc IgG positive
• anti-HBc IgM negative

The serology results are most consistent with which of the following?

A. Acute hepatitis B infection
B. Chronic hepatitis B infection
C. Immunity to hepatitis B from prior infection
D. Immunity to hepatitis B from vaccination
E. None of the above

Correct Answer is C

Comment:

Correct Answer: C

The presence of the combination of anti-HBs and anti-HBc IgG with all other hepatitis B markers being negative suggests immunity from a prior infection. Hepatitis B surface antigen (HBsAg) is a marker of current infection. Hepatitis B surface antibody (anti-HBs) is a marker of immunity through vaccination or previous exposure. Hepatitis B core antibody IgG (anti-HBc IgG) is a marker of previous exposure. Hepatitis B core antibody IgM (anti-HBc IgM) is generally a marker of acute HBV infection, although it can also be positive during spontaneous exacerbation of chronic HBV. 

References:

1. Davison SA, Strasser SI. Ordering and interpreting hepatitis B serology. BMJ. 2014;348:g2522.
2. Dienstag JL. Acute viral hepatitis. In: Kasper D, Fauci A, Hauser S, Longo D, Jameson J, Loscalzo J, eds. Harrison’s Principles of Internal Medicine. 19 ed. New York, NY: McGraw-Hill; 2014.