Hepatitis C Viral RNA, Genotype

The genotyping assay usually requires a minimum viral load of 2,000 IU/mL to successfully obtain a genotype. The limit of detection varies by genotype and ranges from 500 to 5,000 IU/mL.

Since the viral load assay used in this reflex test has a much lower limit of quantitation, it is possible for the patient to have a detectable viral load (below 2,000 IU/mL) and not have a reportable genotype result. Therefore, the Hepatitis C Antibody with Reflex to HCV RNA, PCR with Reflex to Genotype test (test code 94345) does not reflex to HCV genotype if the patient’s viral load is <2,000 IU/mL.

The reflex algorithm allows 3 important HCV tests to be completed, if necessary, with a single blood draw. Each of the 3 tests provides information that is important when a patient enters care.¹

• HCV antibody testing is the initial screening test. A positive result is consistent with prior resolved infection, active infection, or a false-positive antibody, but a supplemental test is needed to confirm active infection.
• The reflex to quantitative HCV RNA testing serves 2 important functions: 1) as a supplemental test to confirm active infection in patients with a positive HCV antibody result and 2) to establish the baseline viral load (concentration of HCV virus in blood). Knowing the viral load at baseline helps physicians monitor response to therapy.
• HCV genotype testing is used to inform treatment decisions.

The tests included in TC 94345 Hepatitis C Antibody with Reflex to HCV RNA, PCR with Reflex to Genotype are recommended for diagnosis and can be used to guide the selection of antiviral treatment.¹ The reflex approach should improve the proportion of patients who have this complete series of important HCV tests performed.²