Interpretation of Hepatitis C Laboratory Results

Table modified from https://www.cdc.gov/mmwr/pdf/wk/mm62e0507a2.pdf.

*Surveillance programs should provide prevention programs with information on people who have positive test outcomes for post-test counseling and referral to treatment and care, as appropriate. No HCV antigen tests have been approved by the US Food and Drug Administration (FDA). When an FDA-approved test becomes available, it will be acceptable laboratory criteria, equivalent to HCV RNA testing. For surveillance purposes, the reporting of positive genotype test results should be considered equivalent to HCV RNA detection, as RNA is required for this test. However, a genotype test in which the genotype cannot be determined is not the same as a “not detected” HCV RNA result.

†Ingestion of high levels of biotin can significantly interfere with certain commonly used biotinylated immunoassays and cause false-positive or false-negative laboratory test results. Currently, the FDA is investigating thresholds associated with false-positive and false-negative tests. Reference: https://www.fda.gov/medical-devices/safetycommunications/update-fda-warns-biotin-may-interfere-lab-tests-fda-safety-communication.

‡Further testing might be recommended if a recent HCV exposure is suspected in the past 6 months (or longer in people who are immunocompromised) or if there is concern regarding the handling or storage of the specimen. If recent exposure is suspected, test for the presence of virus using either a NAT for HCV RNA or a test for HCV antigen (if available). If HCV RNA testing is not feasible, conduct follow-up testing for HCV antibody to demonstrate test conversion.

§If the HCV RNA result is indeterminate, consider provider follow-up to discuss interpretation of result and re-testing strategy.

¶Further testing might be recommended if a recent HCV exposure is suspected in the past 6 months, or if there is concern regarding the handling or storage of the specimen. If distinction between true positivity and biologic false positivity for HCV antibody is desired and the sample is repeatedly reactive, testing with an alternative HCV antibody assay may be useful. In certain situations (e.g., suspected HCV infection within the past 6 months, clinical evidence of HCV infection, and questionable specimen integrity), follow up with another HCV RNA test and appropriate counseling.