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Hepatitis C Diagnosis

Your health care practitioner will interview you about your illness. You will be asked about your symptoms and about any exposures to hepatitis viruses.

If your doctor determines that you may be at risk for contracting hepatitis, you will have blood drawn. The laboratory will be able to determine whether you have acquired HCV and certain other hepatitis viruses.

• Several tests are available for diagnosis, but the most widely used test works by detecting antibodies to HCV. Antibodies are substances made by your body's immune system to defend against a specific infection. It takes time for antibodies to be produced, so the test may be falsely negative if it was performed too soon (less than 4 to 10 weeks) after exposure to the virus. Falsely positive tests may also occur, although the newer tests make this less likely.
• Patients with a positive antibody result should also be tested using a 'PCR' assay. The PCR measures the amount of virus in the blood, known as the 'viral load' or 'viral titer'. A positive viral load indicates active infection and the test may be positive as early as 2 weeks after infection. A negative viral load may mean that the infection has resolved, or it may mean that the infection is active in the liver but not shedding virus into the blood stream at the time the test was done.
• In patients with positive antibodies, tests are also available to identify which of the 6 common genotypes of the virus is causing the infection. This can help determine the best treatment plan. In the United States, genotype 1 is the most common.

The laboratory will also do several tests to determine how well your liver is functioning.

• Other tests will probably be done to check the effects of the infection on other body systems, such as the kidneys.
• If the affected individual has had a large amount of vomiting or have not been able to take in liquids, their blood electrolytes will be checked to see if they are in balance.

Liver biopsy is the ultimate test to determine whether the virus is causing liver damage. It is not necessary for diagnosis, but provides useful information about the stage of disease (the amount of liver damage that has already occurred), and helps to decide whether treatment is needed.