British Liver Trust

A positive result, known as anti-HCV positive, shows that a person has been exposed to the virus at some time. It does not detect whether the virus is still present or whether the person is infectious.

It may take a long time, sometimes a few months, for antibodies to appear in the blood following infection. It is usually eight to twelve weeks after exposure to the virus, but can occasionally be up to six months or more; this means that an antibody test taken too early may not detect exposure to hepatitis C.

The hepatitis C virus itself can be detected by a molecular test called Polymerase Chain Reaction (PCR) to detect hepatitis C viral RNA (HCV RNA). This test is normally done only in people who are anti-HCV positive. If the HCV RNA test is positive, the individual is currently infected. A positive antibody and negative HCV RNA test may indicate a previously cleared infection. Patients who are antibody positive but HCV RNA negative should have a second HCV RNA test after 4-6 weeks to confirm their negative status. However, there can be prolonged periods of up to six months when the virus remains undetectable and then reappears. PCR tests can be requested prior to the antibody test if exposure to HCV is thought to be recent (within 12 to 20 weeks).

Liver function test (LFTs)
Liver function tests (LFTs) are blood tests that measure substances in the bloodstream which indicate that the liver is damaged. However, they are not always good indicators of liver damage and do not detect the presence of the virus. LFT levels can fluctuate throughout the course of the disease. Sometimes they are normal, but this does not prove that liver damage is absent.

Assessing liver damage
Liver biopsy - one way to assess the amount of liver damage is a liver biopsy which involves taking a small sample of liver tissue for examination under a microscope. The test is usually performed under a local anaesthetic. A hollow fine needle is passed through the skin into the liver and a small piece of tissue is withdrawn inside the needle.

Liver biopsy can be uncomfortable, so good pain relief is important, though in some cases the procedure is quite painless. In many hospitals the procedure is performed as a day case, in others an overnight stay is necessary. The results of the biopsy are graded and staged according to the degree of inflammation and scarring.

Following a biopsy, some people feel sore and/or experience some discomfort. Therefore, anyone having a biopsy should think about making arrangements for someone to collect them from the hospital and to take them home.

Predictors of liver scarring – new tests are increasingly available as an alternative to liver biopsy, including blood tests to predict fibrosis and a type of ultrasound called fibroscanning. There are patient benefits of less invasive assessment of the condition of the liver, but further evidence is needed of how these tests compare against the quality and quantity of information available from biopsy.

Strains of hepatitis C
The hepatitis C virus is not a single type of virus. There are different strains (genotypes) of hepatitis C with numerous subtypes.

The prevalence of different strains varies from country to country. In the UK, Western Europe and the United States the most common strains are types 1, 2 and 3. Subtypes are labelled a, b, c, etc. Therefore the patient could have hepatitis C 1a, hepatitis C 2a or hepatitis C 2b, and so on.

It is possible to be infected again with the same, or a different strain, of the virus or be infected with two strains at the same time. Unfortunately, antibodies produced in response to a challenge by the virus do not give protection against a future challenge by the virus .

The different strains do not appear to result in different patterns of disease, but they do differ in their response to treatment.

Because optimum treatment duration and treatment response varies according to the strain of hepatitis C infection, a test is recommended to determine the strain before treatment is advised. Genotype 1 is the most difficult strain to treat with current therapy.

The results of the various tests can be confusing and require specialist interpretation. It is important that people who have hepatitis C are referred to a specialist who should be a hepatologist, or a gastroenterologist with knowledge of liver disease.