Hepatitis C, an inflammation of the liver caused by the hepatitis C virus (HCV), often goes undiagnosed until serious liver problems develop decades after contracting the virus.

This is because the illness is asymptomatic for most people, according to the Centers for Disease Control and Prevention (CDC).

For these asymptomatic people, hepatitis C is generally detected when blood screenings (such as for blood donations) show they are HCV-positive, or routine examinations show they have elevated levels of the liver enzyme alanine aminotransferase (ALT), an indication of liver cell damage.

Who Should Get Tested for Hepatitis C?

Hepatitis C is transmitted when the blood of an infected person gets into an uninfected person's body, such as from sharing needles for intravenous drug use (the most common way people become infected today).

You should get tested for hepatitis C if you:

  • Were born between 1945 and 1965 (adult infection rates were highest in the 1970s and 1980s, according to the CDC)
  • Currently use intravenous drugs or have in the past
  • Received a blood transfusion or organ transplant before July 1992, when routine blood screenings became available
  • Received a clotting factor concentrate made before 1987
  • Are a hemodialysis patient or ever spent many years on dialysis for kidney failure
  • Were born to an HCV-positive mother
  • Have tattoos or piercings
  • Are a healthcare worker who has ever been injured by a needle at work
  • Have HIV
  • Have had unprotected sex with multiple partners or someone known to have HCV
  • Share personal care items with someone who has HCV

However, a 2015 report in the medical journal BMJ questioned whether exhaustive screening for hepatitis C was necessary, or even safe. 

Only a minority of the people with the hepatitis C virus will develop end-stage liver disease, the report's authors noted, and the long-term effectiveness and risks of the new drugs that cure the disease are unknown.

Hepatitis C Diagnosis

There are several tests your doctor may conduct to diagnose you with hepatitis C.

The first diagnostic tool is a blood test that screens for HCV antibodies — proteins the body produces in response to the virus. The most widely used “anti-HCV test” is the enzyme immunoassay (EIA).

A negative result for the antibody test means that you've never had HCV in your blood, while a positive result means you were exposed to the virus at one point in your life (up to a quarter of people spontaneously clear the virus from their blood within six months of contracting it).

Because EIA sometimes produces false-positive results, a test called recombinant immunoblot assay may be used to confirm that you have the HCV antibody.

Additionally, a negative EIA result may just mean your body has not yet produced the HCV antibody, and you may need to be tested again in a few months.

If you have a positive antibody test, your doctor will use another blood sample to conduct a qualitative polymerase chain reaction (PCR) test, which looks for the RNA (genetic material) of HCV in your blood. A positive result means you're currently infected with HCV.

Your doctor may also order a quantitative PCR test or a so-called branched DNA test to determine your HCV viral load, or the concentration of HCV in your blood. The lower your viral load, the more likely you’ll respond positively to treatment.

Other Hepatitis C Tests

Before recommending a treatment plan, your doctor may conduct other tests.

The six major strains, or genotypes, of HCV respond differently to treatment, so your doctor will conduct another blood test that determines your HCV genotype (you may be infected with more than one genotype at a time).

A liver function test, also called the hepatic function panel, looks for elevated levels of bilirubin (a substance produced by the breakdown of hemoglobin) and liver enzymes — including ALT, aspartate aminotransferase, alkaline phosphatase, and gamma glutamyl transpeptidase — in your blood to help determine how much damage your liver cells have sustained.

A liver biopsy, in which a liver tissue sample is removed with a thin needle inserted through your skin and into your liver, can provide more details about the amount of scarring and damage HCV has caused.

Your doctor may also order an imaging test, such as a CT scan, MRI, or ultrasound, to see if your hepatitis C has caused liver cancer, a possible complication of hepatitis C.