From the Guidelines
Anti-HCV antibodies are the appropriate diagnostic marker for Hepatitis C (HCV) in the absence of viral RNA.
Diagnostic Approach
- In the absence of HCV RNA, anti-HCV antibodies can be used as a diagnostic marker for HCV infection, as they persist in the absence of HCV RNA 1.
- HCV core antigen can also be used as a surrogate marker of HCV replication, especially when HCV RNA assays are not available or not affordable 1.
- However, HCV core antigen assays are less sensitive than HCV RNA assays, with a lower limit of detection equivalent to approximately 500 to 3,000 HCV RNA IU/ml 1.
Clinical Considerations
- In cases where HCV RNA is negative, but anti-HCV antibodies are positive, retesting for HCV RNA after 12 and 24 weeks can confirm definitive clearance 1.
- Intermittent HCV RNA positivity has been observed in persons with chronic HCV infection, and a single negative HCV RNA result may not be significant 1.
- Therefore, verifying anti-HCV status is crucial in determining the need for further medical evaluation 1.
From the Research
Diagnostic Markers for Hepatitis C
In the absence of viral RNA, the appropriate diagnostic marker for Hepatitis C (HCV) can be considered as follows:
- HCV core antigen is a direct virological marker that can detect HCV infection with a pooled sensitivity of 0.84 and specificity of 0.98 2
- IgM antibodies to hepatitis C virus have been found in a variable proportion of patients with chronic hepatitis C and may be useful as an adjunct in the clinical assessment of patients with chronic hepatitis C 3
- HCV core antigen assays may not displace HCV RNA assays for definitive diagnosis but can be a promising method as a confirmatory test for HCV antibody positive, therapy-naive individuals 2
Comparison of Diagnostic Markers
The following points compare the different diagnostic markers:
- HCV RNA detection by polymerase chain reaction (PCR) assay is the gold standard for the diagnosis of HCV infection 4
- HCV core antigen has lower analytical sensitivity than HCV RNA for the detection of low viremia levels but has advantages such as lower cost and greater stability of the target 5
- Quantification of HCV RNA (viral load) is the most widely used marker to diagnose and confirm active HCV infection 5
Clinical Utility of Diagnostic Markers
The clinical utility of the diagnostic markers can be considered as follows:
- HCV core antigen testing can be used to identify patients with active HCV infection and has been shown to be useful in several studies and guidelines 5
- IgM anti-core hepatitis testing may prove useful as an adjunct in the clinical assessment of patients with chronic hepatitis C 3
- HCV genotype determination and HCV RNA quantification can be used to tailor treatment to the individual patient and to determine its efficacy 6