Approach to HBsAg-Positive Patients

You answered:

A The next appropriate blood test is a hepatitis B core antibody (anti-HBc), which alone can determine if the patient has acute hepatitis B infection.

This answer is incorrect. The standard assay for anti-HBc detects total anti-HBc, and does not distinguish between IgG and IgM components. The anti-HBc IgG isotype appears approximately 4-6 months after acute hepatitis B infection, and remains positive for life. Thus, detection of anti-HBc does not indicate acute hepatitis B infection. In this patient, it is not yet clear whether he has acute or chronic hepatitis B infection, because he has never had HBsAg measured in the past. He requires a complete hepatitis B serology as part of the workup of hepatitis B infection. This should also include a test for IgM anti-HBc.

Choose another answer:

B The most appropriate blood test is a hepatitis B e antigen (HBeAg), which alone can determine if the patient is an inactive carrier of hepatitis B or if he is actively infected.
C No further blood work is necessary. The finding of positive HBsAg alone is enough to define the patient as a chronic hepatitis B carrier, and he should be screened for hepatocellular carcinoma with a serum alpha-fetoprotein measurement and abdominal ultrasound.
D Appropriate laboratory studies should include a complete hepatitis B serologic evaluation, a serum HBV DNA level, and biochemical markers related to hepatic inflammation and function.

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