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Blood Test Tracker

Hepatitis C Antibody

Checks for antibodies your immune system makes after hepatitis C exposure. A reactive result is followed by an RNA test to see if the virus is still there.

AI-verified against cited sources. Awaiting expert reviewAlso called HCV Ab, Anti-HCV, HCV-AbLOINC 16128-1

What it is

Hepatitis C is a virus that infects the liver. When your body meets it, your immune system makes antibodies. This test looks for those antibodies in your blood. Antibodies show that you have been exposed at some point. They do not show whether the virus is still in your body. That is why a reactive result is usually followed by a hepatitis C RNA test. Some labs print a signal-to-cutoff (S/CO) number next to the result.

Why it matters

This is the usual first step in testing for hepatitis C. CDC recommends that all adults 18 and older be tested at least once, that pregnant people be tested during each pregnancy, and that people with ongoing risk be tested regularly. Finding hepatitis C matters because it can quietly affect the liver for years and it can be treated. A reactive antibody result needs the RNA follow-up test to show whether there is a current infection.

If it’s high

Reactive (positive) means hepatitis C antibodies were found. The reasons include a past infection that has cleared, a current infection, or, less often, a false-positive result. The antibody test alone cannot tell these apart. The RNA test is what shows whether the virus is in your blood now, and many labs can run it automatically on the same sample.

Common causes

  • A past hepatitis C infection that cleared on its own or after treatment
  • A current hepatitis C infection, new or long-term
  • A false-positive result, which is uncommon, where the test reacts even though you were not exposed

What can help

  • Check that the RNA test was run, since many labs do it automatically on the same sample
  • Ask your clinician what the RNA result means for you
  • If the RNA is not detected and the antibody result is unexpected, ask whether a second antibody test makes sense

If this applies to you

HCV antibody means a little more for some people. Open the one that fits you.

Fatty liver or liver condition

CDC recommends a hepatitis C test at least once for all adults 18 and older, and AASLD lists it in the fatty liver workup for anyone not tested before. A reactive antibody result is followed by an RNA test to see whether the virus is still there.

Blood tests for liver health

Taking HIV PrEP

The CDC suggests hepatitis C testing before starting and every 12 months for gay, bisexual and other men who have sex with men, transgender women who have sex with men, and people who inject drugs.

Blood tests on HIV PrEP

What can affect your result

  • Time since exposure: antibodies may not be detectable until after about 2 months, so a very early negative result can be too soon to trust
  • Past infection: antibodies usually stay reactive after the virus has cleared
  • Biotin supplements: Mayo asks people to avoid them for 24 hours before the draw
  • The test brand and its cutoff, which differ between labs
  • False-positive results can happen
  • Mayo Clinic Laboratories asks you not to take multivitamins or supplements that contain biotin (vitamin B7), such as hair, skin and nail products, for 24 hours before the draw.
  • Testing too soon after exposure can miss an infection. Mayo notes that antibodies may not be detectable until after about 2 months, while an RNA test can find the virus about 1 to 2 weeks after exposure (CDC).
  • A reactive result can be a false positive. A second, different antibody test can help sort out true from false reactivity (Mayo).

Antibodies may not show up until about 2 months after exposure. Once present, they usually stay reactive even after the virus has cleared on its own or with treatment.

When to talk to a clinician

Talk with your clinician soon about any reactive result. If you may have been exposed in the last 6 months and your antibody result was non-reactive, ask about an RNA test now or a repeat antibody test at least 6 months after the exposure. Get medical care promptly for yellow skin or eyes, a swollen belly, vomiting blood, black stools or confusion.

Questions you could ask

  • How often should I be retested, given my situation?
  • Was an HCV RNA test run on this sample, and what did it show?
  • What else do we need to find out whether the infection is current?
  • Would a second antibody test help check for a false positive?
  • Could a recent exposure be too early for this test to show?

Questions people ask

My antibody test was reactive. Does that mean I have hepatitis C?

Not necessarily. It means antibodies were found. That can come from a past infection that cleared, a current infection, or a false positive. The RNA test shows whether the virus is in your blood now.

If my result is non-reactive, can I be sure I don't have it?

A non-reactive result usually means you have not been exposed. But antibodies can take about 2 months or longer to show up after infection, so a recent exposure can be missed. Ask about an RNA test if you may have been exposed in the last 6 months.

Who should be tested for hepatitis C?

CDC recommends testing all adults 18 and older at least once, testing during each pregnancy, and regular testing for people with ongoing risk. Ask your clinician what fits your situation.

Show the science and sources

For clinicians and researchers

Most labs use an automated immunoassay (Mayo Clinic Laboratories uses an electrochemiluminescence immunoassay, ECLIA) and report reactive or non-reactive, sometimes with a signal-to-cutoff ratio whose cutoff is set by the manufacturer. CDC (2013) states that a reactive result means current infection, past resolved infection, or false positivity. CDC (2020) recommends one-time screening of all adults 18 and older except where HCV RNA prevalence is below 0.1%, screening in each pregnancy, periodic testing while risk continues, and reflex RNA testing after a reactive antibody. AASLD-IDSA (updated 2024) recommends antibody testing with reflex RNA PCR for initial testing. A reactive antibody with undetectable RNA means no laboratory evidence of current infection, and the person can still be reinfected. Among people with a negative antibody who were exposed in the past 6 months, RNA or follow-up antibody testing 6 or more months after exposure is recommended. Mayo notes that antibodies may not be detectable until after about 2 months, that RNA testing is needed for suspected acute infection, and that a second FDA-approved antibody assay from a different manufacturer can help separate true from false-positive reactivity. Mayo reports a normal result as 'Negative'. How to read an S/CO ratio depends on the assay and was not checked for individual manufacturers.

LOINC 16128-1 (primary), 13955-0, 40726-2, 48159-8. Specimen: serum.

Sources

  1. Hepatitis C Virus (HCV) Antibody Screen with Reflex to HCV RNA, PCR, Asymptomatic, Serum (test HCSRN), Mayo Clinic Laboratories
  2. Hepatitis C Virus (HCV) Antibody with Reflex to HCV RNA, PCR, Symptomatic, Serum (test HCVDX), Mayo Clinic Laboratories
  3. Clinical Screening and Diagnosis for Hepatitis C, CDC
  4. CDC Recommendations for Hepatitis C Screening Among Adults, United States, 2020, MMWR Recommendations and Reports (2020)
  5. Testing for HCV infection: an update of guidance for clinicians and laboratorians, MMWR (2013)
  6. HCV Testing and Linkage to Care, AASLD-IDSA HCV Guidance (2024)

AI-verified against cited sources. Awaiting expert review. Last reviewed 2026-10-03. How we build and check these pages.

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