Q&A Medicine>>>>>Gastroenterology
Question 2#

A 29-year-old woman presents to the physician because of fatigue, dark urine, nausea, vomiting, and decreased appetite. She reports that the symptoms started 1 month ago and have worsened in the last week. She has an insignificant past medical history but does endorse IV drug use as well as unprotected sexual intercourse with several partners over the last 6 months. She is unable to recall her immunization history. Laboratory results show elevated AST (210 U/L) and ALT (352 U/L) levels. The physician determines she is at high risk for hepatitis B virus.

What laboratory test(s) should be ordered to screen for ACUTE hepatitis B infection? 

a. Anti-HBe
b. HBsAg and anti-HBs
c. HBeAg
d. HBsAg and IgM anti-HBc

Correct Answer is D

Comment:

HBsAg and IgM anti-HBc. Testing for HBsAg and IgM anti-HBc is the best screening test for acute hepatitis B infection. HBsAg is the first marker detected in the blood after exposure and actually occurs before elevation in AST/ALT levels or clinical symptoms. HBsAg can be detected throughout the symptomatic phase of acute hepatitis B infection and its presence is indicative of infectivity. Anti-HBc appears shortly after HBsAg appears and the IgM component indicates the acute phase of the disease, whereas the IgG component indicates recovery from the disease. The period between the disappearance of HBsAg and the appearance of anti-HBs is called the “window period.” IgM anti-HBc is present during the “window period” when anti-HBs is not yet detectable and thus is used as a marker for the diagnosis of acute hepatitis. (A, B, C) HBeAg appears soon after HBsAg appears and indicates active viral replication and very high infectivity. It is followed by anti-HBe, and its presence for more than 3 months signifies an increased probability of chronic hepatitis B. Anti-HBs is present in individuals who have been vaccinated or have cleared HBsAg; thus it is present for life.