Diagnosis of hepatitis C (HCV) is first made using blood tests that measure antibodies to HCV, and then confirmed with tests to detect the presence of the virus or HCV RNA. Other tests are also used to make treatment choices, to determine the stage of the disease, and to predict how the disease will progress.
Antibody and HCV RNA testing
As part of an initial evaluation for HCV infection, your doctor will first give you an antibody test. If the antibody test is positive (indicating that you have been exposed to HCV), then your doctor will give you a second test determine whether HCV (specifically HCV RNA) is in your body. This test is often called a viral load test or just viral load.1
Learn more about viral load.
If you have antibodies to HCV, but no evidence that the virus is in your body, it usually means that you were once exposed to HCV and your body cleared the virus. Although, most people who develop acute HCV infection (with detectable HCV RNA) go on to develop chronic HCV infection, the US Centers for Disease Prevention (CDC) estimates that about 20% clear HCV on their own. It is also possible that the antibody or viral load tests were not accurate, so talk to your doctor about whether you should be retested.1
Who should be tested for chronic HCV infection?
If you have evidence of liver disease (either from signs and symptoms or from abnormal liver function testing) or if you have HCV risk factors or exposures, your doctor will test you for chronic HCV infection. According to the CDC, HCV testing is recommended for2:
- Persons born between 1945 and 1965 (Baby Boomers)
- Persons with a history of risk behaviors
- Injection-drug use (current or lifetime, including those who only injected once)
- Intranasal illicit drug use
- Persons with risk exposures
- Long-term hemodialysis
- Having a tattoo in an unregulated setting
- Healthcare, emergency medical, and public safety workers with needlesticks, sharps, or mucosal exposure to HCV-infected blood
- Children born to HCV-infected women
- Prior transfusion and transplant (organ) recipients, including:
- Those who were notified of having received blood from a donor who tested HCV-positive
- Those who received a transfusion or blood components, or had an organ transplant before July 1992
- Those who received clotting factor concentrates produced before 1987
- Persons with selected medical conditions
- HIV infection
- Unexplained chronic liver disease, chronic hepatitis, including elevated liver enzyme alanine aminotransferase levels
Additional diagnostic evaluation
If you are diagnosed with HCV infection, your doctor will assess the extent of liver damage to determine if you are a candidate for antiviral treatment, and to consider factors that affect response to treatment.
The decision to start antiviral drug therapy will depend on several factors, including how quickly the disease is progressing, the stage of fibrosis, and the presence of other health conditions. Your doctor will use the physical examination to detect signs of advanced liver disease. Certain conditions, such as active drug use, severe kidney disease, and being pre- or post-liver transplant add an extra layer of complication when it comes to treatment decisions. These conditions may cause treatment delays. You may be referred to a liver specialist who treats more complicated cases. 1 With the availability of new, safer HCV antiviral medications, treatment is safe for nearly everyone. However, antiviral therapy should not be prescribed if you are pregnant or breastfeeding.
History and physical exam. Your doctor will take your medical history and give you a thorough physical exam. The history will include questions related to factors that may accelerate the progression of HCV, including alcohol and drug use, complications suggesting advanced cirrhosis (e.g., ascites), and other underlying health conditions that may affect whether you are a candidate for antiviral treatment (e.g., pregnancy, breastfeeding, active drug use, kidney disease). Your doctor needs to know all the medications and supplements you take. Certain drugs and herbs interfere with some HCV medications, so be sure to mention everything you take, whether prescription or nonprescription.
Laboratory testing. Several lab tests will be used to determine the extent of liver disease, assess your general health, and identify other health conditions that may affect whether you are a candidate for antiviral treatment. These will include 1:
- Liver tests (or liver panel). This blood test assesses how well your liver is functioning and includes liver enzymes alanine transaminase (ALT) and aspartate transaminase (AST), bilirubin, and albumin.
- Prothrombin time. This test measures your clotting time, which reflects how well your liver is functioning.
- Complete blood count. This test measures levels of white and red blood cells, hemoglobin, and platelets. Platelets are especially important to monitor, because if they drop to below normal, it could be an indication of cirrhosis.
- Kidney function, blood glucose and lipid levels, and thyroid function tests
- Vitamin D
- Pregnancy. Antiviral treatments should not be used in people who are pregnant or trying to become pregnant.
HCV genotyping. Choice of antiviral treatment regimen, including selection of drugs, dosing, and duration of treatment, depends on HCV genotype. The HCV family of viruses is made up of 7 different genotypes, with numerous subtypes. These HCV genotypes and subtypes respond differently to different treatment regimens. So, determining HCV genotype and subtype is crucial for selecting the appropriate treatment regimen.1
Learn more about HCV genotype and its importance in treatment decisions.
Liver biopsy. Your doctor may want to perform a liver biopsy if he or she thinks that the results will provide important guidance in managing your disease. Liver biopsy is used to determine the stage of fibrosis (scarring) and inflammation. Knowing the stage of fibrosis helps you and your doctor know how advanced your liver disease is, and determine the timing of antiviral therapy. For instance, if there is little progression of fibrosis, your doctor may recommend waiting for approval of a treatment that may be more effective or easier to tolerate. Liver biopsy is generally safe, but it is invasive and, therefore, associated with some risk for complications. 1 Liver biopsy has long been the preferred approach for assessing the extent of liver disease, but noninvasive techniques are improving and gaining popularity.
Learn more about liver biopsy and its usefulness in HCV
Noninvasive approaches to assess liver function. Although liver biopsy has been the “gold standard” for evaluating the severity of chronic HCV infection, some providers prefer noninvasive tests to measure the degree of fibrosis. There are two general types of noninvasive tests for fibrosis: (1) blood tests and (2) imaging tests. 3,4
Testing for HIV, hepatitis B, and hepatitis A. If you are diagnosed with HCV infection, your doctor may test you for other types of infections, including HIV, hepatitis B, and hepatitis A. HIV and hepatitis B infections share common modes of transmission with HCV. Co-infection with HCV and HIV will affect your choice of HCV treatment. Checking for hepatitis A and hepatitis B will determine if you are already immune or infected. If you are not, you should receive vaccinations for both hepatitis B and hepatitis A. 1