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Viral Load Monitoring During Antiviral Therapy for Chronic Hepatitis C – What Test Should I Use?

July 2014

An estimated 3.2 million persons in the United States have chronic hepatitis C virus (HCV) infection.1 HCV is the primary cause of cirrhosis, hepatocellular carcinoma (HCC), and end-stage liver disease requiring liver transplantation. Current management of chronic hepatitis C is aimed at halting disease progression, preventing cirrhosis decompensation, reducing the risk of HCC, and treating extrahepatic complications of the infection.

Because of the slow evolution of chronic hepatitis C over several decades, it is difficult to demonstrate that therapy prevents complications of liver disease. Accordingly, treatment responses are defined by a surrogate virological parameter rather than a clinical endpoint.2 The latest recommendations from the American Association for the Study of Liver Disease (AASLD), the Infectious Diseases Society of America,3 as well as the product inserts for the FDA-approved anti-HCV therapy with these agents (telaprevir, broceprevir, simeprevir, and sofosbuvir) now indicate that patients receiving these agents should be tested with a HCV RNA assay that can quantify down to 15 IU/mL in serum or plasma.

Mayo Medical Laboratories offers an assay that meets these new requirements: HCVQU / Hepatitis C Virus (HCV) RNA Detection and Quantification by Real-Time Reverse Transcription-PCR (RT-PCR), Serum. This test is FDA approved with the lower and upper limits of quantification at 15 and 100,000,000 IU/mL, respectively, and Mayo Medical Laboratories recommends this assay as the molecular diagnostic test to detect and quantify HCV RNA. The analytical sensitivity of this assay is as good as, if not better than, some of the current commercially available qualitative HCV RNA detection assays. This assay has been validated by Mayo Medical Laboratories for use to confirm the presence of chronic HCV infection, to determine pretreatment (baseline) HCV RNA levels in serum, and to monitor a patient’s response to antiviral therapy.

There are 4 possible results from this assay (HCVQU):

  1. Undetected: HCV RNA is absent.
  2. Detected, but <15 IU/mL: HCV RNA is detected, but the level present is <15 IU/mL, and cannot be accurately quantified below this level.
  3. Quantitative Value: The quantitative result indicates the degree of active HCV viral replication in the patient (eg, 15,000 IU/mL). Monitoring HCV RNA levels over time is important to assess disease progression and/or a patient’s response to anti-HCV therapy.
  4. Detected, but >100,000,000 IU/mL: HCV RNA level detected is >100,000,000 IU/mL and indicates the presence of active HCV viral replication. The HCV RNA level present cannot be quantified accurately above this upper limit of quantification of this assay.


  1. CDC Hepatitis C Information for the Public. Available from http://www.cdc.gov/hepatitis/c/cfaq.htm#cFAQ13. Accessed May 20, 2014
  2. Ghany MG. Strader DB, Thomas DL, Seeff LB, American Association for the Study of Liver Diseases: Diagnosis, management, and treatment of hepatitis C: An update. Hepatology 2009 Apr;49(4):1335-1374
  3. Recommendations for Testing, Managing, and Treating Hepatitis C. American Association for the Study of Liver Diseases and Infectious Diseases Society of America. Available from http://www.hcvguidelines.org/full-report-view. Revised date: March 21, 2014. Accessed May 20, 2014