![]() To determine whether a patient has achieved a sustained virologic response (SVR).To monitor a patient's response to therapy.To measure a patient's baseline viral load prior to starting HCV therapy.To confirm a positive HCV Ab result and make the diagnosis of current HCV infection.There are 4 major reasons that HCV RNA tests are used: The HCV RNA tests can detect virus within 1-2 weeks following exposure. Therefore, a positive HCV Ab screening result must be followed by a test for the HCV RNA. The presence of HCV RNA is required to confirm chronic HCV infection. The RIBA test is no longer in use or available in the United States. It still required HCV RNA testing for the diagnosis of chronic infection. Recombinant immunoblot assay (RIBA) is a highly specific test that in the past was used as a confirmatory test of antibody results. Recombinant Immunoblot Assay for Confirmation of HCV Ab The sensitivity and specificity of the test is similar to that of the laboratory-based assays. Just as for the standard HCV Ab test done in the lab, a positive OraQuick ® test must be confirmed by an HCV RNA test. Results are reported as reactive or nonreactive within 20 minutes. It is also a CLIA-waived test and therefore can be used in clinic offices and outreach facilities. The OraQuick ® HCV Rapid Antibody Test is an FDA-approved test that can be performed with a fingerstick (or venous blood draw). Many labs do not perform the tests on site and must send specimens to another lab for processing, which may further increase the turnaround time.Ī point-of-care test is also available. The turnaround time for 3rd-generation EIAs is at least 1 day. A false-positive HCV Ab result may occur because of cross-reactivity with other viral antigens or the presence of immunologic disorders, such as lupus or rheumatoid arthritis.If the HCV Ab result is negative in immunocompromised patients, but there is strong suspicion of HCV infection, it would be appropriate to order the HCV RNA test. A false-negative HCV Ab result may also occur in immunocompromised individuals such as those infected with HIV, recipients of organ transplants, and patients receiving chronic hemodialysis.If the HCV Ab test result is negative within the first 8 weeks after infection, it would be appropriate to retest the antibody after 8 weeks to check for seroconversion. The average time from infection until seroconversion is 8 weeks and is referred to as the "serologic window." If acute infection is suspected to have taken place within the past 8 weeks, it would be appropriate to order the HCV RNA test. A false-negative HCV Ab result may occur if the test is performed during the window period after acute HCV infection but before seroconversion (when the HCV Ab converts from negative to positive).A positive antibody test result should be followed up with an HCV RNA test to confirm that viremia is present.įalse-Negative and False-Positive HCV Ab Resultsĭespite the extremely high sensitivity and specificity of the EIA test for the antibody, it is still possible to have both false-positive and false-negative results. However, the presence of HCV Ab does not indicate whether the infection is acute, chronic, or resolved. Third-generation EIAs have a sensitivity/specificity of approximately 99%. The result of the test is reported as positive or negative. ![]() The test is performed by enzyme immunoassays (EIAs), which detect the presence of hepatitis C antibodies in serum. The HCV Ab test is used for initial screening for hepatitis C. HCV Serologic Testing (HCV Ab) Enzyme immunoassays for Detection of Hepatitis C Antibody Drug resistance: Mutations of some proteins in HCV can allow the virus to have resistance to direct-acting antivirals (DAAs), commonly referred to as resistance-associated variants (RAVs) or resistance-associated polymorphisms (RAPs).Genotype: Once it is determined that HCV RNA is present, the specific genotype and subtype of the virus can be determined with a genotype test.Confirmatory: Diagnosis of chronic hepatitis C requires the presence of HCV RNA, commonly called hepatitis C viral load.Screening: Screening for hepatitis C virus (HCV) is done with a serologic test for the HCV antibody (Ab).Laboratory tests for hepatitis C are divided into four general categories: VA Software Documentation Library (VDL).Clinical Trainees (Academic Affiliations).War Related Illness & Injury Study Center. ![]()
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