Test your medicine knowledge with the MKSAP challenge, in partnership with the American College of Physicians.
A 55-year-old man is evaluated in follow-up after a recent routine screening for antibody to hepatitis C virus (HCV) was positive. His medical history is unremarkable; he has not used illicit drugs or had any history of blood transfusions. He currently feels well and takes no medications.
Vital signs and physical examination are normal.
Laboratory studies reveal a positive HCV antibody test, but HCV RNA testing is negative. The serum alanine aminotransferase level is normal.
Which of the following is the most appropriate diagnostic test to perform next?
A: Perform liver ultrasound
B: Perform serial alanine aminotransferase monitoring
C: Repeat HCV antibody testing
D: Repeat HCV RNA testing
E: No further testing
MKSAP Answer and Critique
The correct answer is E: No further testing.
Patients who are hepatitis C virus (HCV) antibody positive but HCV RNA negative do not have HCV infection and require no further testing. Repeating HCV RNA testing can be considered if there are risk factors for recent HCV infection or if there is other clinical evidence of liver disease, but neither of these is present in this patient. A 2013 guideline from the U.S. Preventive Services Task Force recommended screening for hepatitis C once in all persons born between 1945 and 1965, as well as targeted screening of persons with risk factors such as illicit drug use, receipt of blood products, hemodialysis, and multiple sex partners. Screening is accomplished by testing for antibody to HCV (anti-HCV). If antibody testing is positive, the next step is to perform HCV RNA testing, which is often done by “reflex” testing in many laboratories. The test results are interpreted in the following ways: Positive anti-HCV with negative HCV RNA indicates either false-positive anti-HCV or cleared infection, and positive anti-HCV with positive HCV RNA indicates active infection. Rarely, in instances of acute HCV infection or in an immunosuppressed patient, HCV RNA may be positive despite a negative anti-HCV.
Liver ultrasound and serial alanine aminotransferase monitoring are not necessary in the absence of clinical evidence of liver disease.
Key Point
- Patients with a positive antibody to hepatitis C virus (HCV) but negative HCV RNA do not have HCV infection, and no further testing is required.
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