Hepatitis C is diagnosed using careful questioning, a thorough physical examination, and through laboratory and imaging tests. Your healthcare professional will ask about your symptoms and how long you have been having them. You may also be asked about your history of risk factors such as
- blood transfusions,
- injection drug use,
- tattoos and piercings,
- sexual partners, and
- exposure to other people who do or might have hepatitis C.
What laboratory tests diagnose hepatitis C?
Laboratory blood tests will be done to evaluate the patient's liver function (liver blood tests) and to look for hepatitis C antibodies (serologies). If these tests indicate that the person has hepatitis C, a hepatitis C "viral load" test will be done. This looks for genetic material from the hepatitis C virus (HCV) and measures the quantity of hepatitis C virus that is circulating in the patient's blood. This is helpful in determining if treatment is appropriate and to monitor the success of the treatment (how well the patient responded). Individuals who had hepatitis C in the past and cleared the virus on their own will have a positive HCV antibody test, but there will be no hepatitis C virus genetic material (undetectable viral load) in the blood. If a person is immunosuppressed due to an immunological condition, cancer chemotherapy, immunotherapy or HIV/AIDS, the test results may be different and need to be evaluated accordingly.
What other tests diagnose hepatitis C?
Once the diagnosis of hepatitis C is established, other tests may be done to determine whether the patient has developed liver fibrosis or scarring (cirrhosis). This can be done with a needle biopsy of the liver, and examining the biopsied liver tissue under the microscope. Liver biopsy is less commonly done today because non-invasive tests (without invading the liver) are more readily available, more easily accomplished and less costly.
Liver imaging can evaluate fibrosis using ultrasound and MRI scans. Additionally, calculations using a variety of blood tests (FibroSure, FibroTest, Hepascore, FibroSpect, APRI) also can predict the degree of inflammation and fibrosis present. Genotype testing will typically be done to determine what subtype of hepatitis C the patient has, as this will impact what drugs are used for treatment. Testing for other infections including HIV, hepatitis A, and hepatitis B also are typically done to determine if the patient might have other conditions that could impact patient's treatment and prognosis.