Hepatitis C – Diagnostic Serology

Testing Indications

Testing for Hepatitis C Virus (HCV) antibodies is indicated for the work-up of patients with suspected chronic viral hepatitis or those with unexplained elevation in their liver function tests (e.g. ALT, AST), for screening those at high risk of infection (e.g. intravenous drug users, etc.), for determining past exposure, and as part of an epidemiologic investigation (e.g. infection control breach). Testing for HCV antibodies during the work-up of a patient with suspected acute viral hepatitis is for baseline purposes as there is no HCV IgM test currently available.

Specimen Collection and Handling

Specimen Requirements

Test Requested Required Requisition(s) Specimen Type Minimum Volume Collection Kit

Hepatitis C

Serum

1.0 mL

Serum Separator Tube (SST)

Submission and Collection Notes

1

Detailed instructions for ordering Hepatitis C testing are available to assist you with completing the “Hepatitis Serology boxes” in section 3 of the General Test Requisition.

2

Public Health Ontario (PHO) prefers centrifuged SST for serological assays. Instructions for using SST tubes are found in the document titled: LAB-SD-008 Blood Collection Using Serum Separator Tubes.

3

If testing for a combination of hepatitis virus markers, HIV, HTLV, syphilis, and rubella, you are only required to submit one FULL 6 – 8.5 mL SST. If a full tube cannot be drawn, submit two tubes.

4

Do not submit glass tubes.

Limitations

Haemolysed, icteric, lipemic or microbially contaminated serum is not recommended for testing.

Preparation Prior to Transport

Label the specimen container with the patient’s full name, date of collection and one other unique identifier such as the patient’s date of birth or Health Card Number. Failure to provide this information may result in rejection or testing delay.

Centrifuge SST. Place specimen in biohazard bag and seal. Specimens should be stored at 2-8°C following collection and ship to PHO’s laboratory on ice packs within 3 days of collection. Specimens received more than 7 days post collection will not be tested. If delayed shipping is anticipated, remove serum from clot and store frozen at -20°C or colder and ship on dry ice.

Requisitions and Kit Ordering

Test Frequency and Turnaround Time (TAT)

HCV serology testing is performed daily Monday to Friday.

Turnaround time is up to 3 days from receipt by PHO’s laboratory for non-reactive specimens and up to 6 days for reactive and indeterminate specimens.

Testing of ‘Source Patient’ for needlestick/occupational exposure, if warranted.

Reporting

Results are reported to the ordering physician or health care provider as indicated on the requisition.

Specimens that are reactive for HCV antibody are to be reported to the Medical Officer of Health as per Health Protection and Promotion Act.

Test Methods

Specimens for HCV antibody are initially tested using a chemiluminescent microparticle immunoassay (CMIA) for the qualitative detection of HCV antibody in human serum. Reactive specimens are tested using a supplemental HCV antibody assay for confirmation.

Interpretation

Final results for HCV antibody are based on the results of both the screening and supplemental tests.

A negative HCV antibody test result indicates absence of infection with HCV. Repeat testing may be indicated in those with ongoing risk factors for the acquisition of HCV.

A confirmed reactive HCV antibody result is evidence of infection with HCV. It cannot distinguish between recent or past infection. In addition, a positive HCV antibody result does NOT indicate immunity to hepatitis C virus. Once a patient tests positive for HCV antibody, other than in cases of maternal antibody transfer, there is no value in repeating the test as they will remain antibody positive for life regardless of whether they have cleared the virus or are chronic carriers.

An inconclusive result for HCV antibody (reported when the screening test is positive, but the supplemental test is negative OR when the CMIA screen is indeterminate) may be due to early infection in which case, a complete antibody response has not yet developed or it may be due to a biological false positive result due to cross-reacting or non-specific antibodies. Follow up testing on a fresh sample is indicated.

HCV RNA testing is recommended for individuals with a reactive or inconclusive HCV antibody result to determine if they are have active infection. Refer to the Hepatitis C – RNA Viral Load Test Information Sheet for information.

Refer to LAB-SD-020: Hepatitis C Virus (HCV) Antibody Testing for more information on interpretation and follow-up testing.

Mis à jour le 10 mars 2022