Hepatitis C Diagnostics

Serological Tests

Anti-HCV antibodies are the first-line diagnostic test in individuals with suspected HCV infection and are determined via enzyme immunoassay or enhanced chemiluminescent immunoassay in plasma or serum. HCV RNA (or HCV core antigen) should be determined to identify viremia or current HCV infection in patients with detected anti-HCV antibodies. HCV antibody screening with reflex HCV RNA testing is the recommended initial HCV testing to determine the presence of active infection. Acute hepatitis C can be reliably diagnosed if recent seroconversion to anti-HCV antibodies (ie a prior negative HCV antibody test becomes positive) can be documented; however, antibody tests often do not become positive until 3 months after infection. If the clinical suspicion is high, the patient should be tested for HCV RNA (or HCV core antigen) to establish the diagnosis. If HCV RNA is positive and anti-HCV is negative, patients have an early acute HCV infection. Follow-up HCV antibody testing at least 6 months after an initial negative HCV antibody test following an exposure can be an alternative to HCV RNA testing.  

Chronic hepatitis C is a continued HCV infection of ≥6 months after acquiring the disease and is diagnosed based on the presence of both anti-HCV antibodies and HCV RNA (or HCV core antigen). If HCV RNA is positive and anti-HCV is negative, it indicates a chronic HCV infection in an immunocompromised host.   

HCV RNA quantitative testing to determine baseline viral load is recommended before starting antiviral therapy. This is used to detect current (acute and chronic) infection and evaluate treatment response. If HCV RNA is negative and anti-HCV is positive, it may indicate a resolved HCV infection, an acute HCV infection during low-level viremia or a false-negative HCV RNA test. Repeat HCV RNA (recommended quantification threshold ≥15 IU/mL) and anti-HCV testing in 3-6 months. HCV RNA quantitative testing is also a recommended test for assessment of HCV recurrence. HCV RNA levels do not correlate significantly with the degree of hepatic inflammation or fibrosis and, in the absence of antiviral therapy, remains relatively stable.  

Undetectable HCV core antigen can be an alternative endpoint of therapy in patients with detectable HCV core antigen before therapy. 

HCV genotype, including subtyping of genotype 1a/1b, should be determined, if possible (if a non-pangenotypic regimen will be prescribed), in all HCV-infected persons prior to treatment to determine type and duration of therapy and chances of response. Predominant genotypes in Asia are: Genotypes 1b and 2 for East Asia (China, Taiwan, South Korea, and Japan); genotype 3 for South Asia (India and Pakistan) and genotype 3 is considered difficult to treat and is associated with a poor prognosis; and genotypes 1 and 6 for Southeast Asia (Vietnam, Cambodia, Laos, Indonesia, Myanmar, Malaysia, Philippines, and Thailand). It must be noted that genotypes 1 and 3 are predominant across most countries regardless of economic status, while genotypes 4 and 5 are found predominantly in low-income regions.

Liver biopsy is the gold standard for detecting liver fibrosis and/or cirrhosis and may provide prognostic information; although, biopsy is not mandatory to start therapy. This is an invasive procedure and is associated with increased risk of morbidity and mortality.

Depending on local health services, the following groups should be tested for chronic HCV infection: Persons who have in the recent or remote past used illicit IV/intranasal drugs, or men who have sex with men (MSM); and persons with conditions associated with high prevalence of HCV infection (positive HIV, sexually active individuals taking pre-exposure prophylaxis for HIV, hemophiliacs who received clotting factor prior to 1987, patients with Hansen’s disease, history of hemodialysis, persons who received blood/blood products or organ transplants prior to July 1992, children born to HCV-infected mothers, healthcare workers after a needle stick injury or mucosal exposure to HCV-positive blood, current sexual partners of HCV-infected persons, and incarcerated individuals).

Screening Tests to Rule Out Other Viral Hepatitis  

The screening tests to rule out other viral hepatitis are: For hepatitis A, request for anti-hepatitis A virus (anti-HAV) IgM and nucleic acid amplification test (NAAT) for HAV RNA may be considered; for hepatitis B, request for hepatitis B surface antigen (HBsAg) and hepatitis B core antibody (anti-HBc); for hepatitis D, request for anti-hepatitis D virus (anti-HDV) antibody; and for hepatitis E, request for IgM anti-HEV.  

Please see Hepatitis A and E and Hepatitis B disease management charts for further information.  

Other Recommended Lab Tests in Patients Suspected of Viral Hepatitis







The laboratory tests recommended in patients suspected of viral hepatitis within 6 months prior to starting therapy are: Liver function tests (LFTs), aspartate aminotransferase (AST) and alanine aminotransferase (ALT), serum albumin, bilirubin, alkaline phosphatase (ALP), prothrombin time (PT), international normalized ratio (INR), complete blood count (CBC) with platelets, and estimated glomerular filtration rate (eGFR). Non-invasive tests such as the aminotransferase/platelet ratio index (APRI) or fibrosis-4 (FIB-4) must be used to assess the degree of hepatic fibrosis when resources are limited prior to initiating HCV therapy.