Several diagnostic tests currently are available for the diagnosis of HCV infection. They can be categorized according to the way the tests are used.

Screening tests are tests that are used to diagnose a condition or disease among individuals not known to have the disease. They are particularly useful for individuals who have risk factors for the condition or disease.

The first step in screening for HCV infection is to test blood for the antibody to HCV using an enzyme immune-assays (EIAs) test. If the EIA test is negative (does not find the antibody), the patient is assumed to be free of HCV. It takes several weeks or up to six months for antibodies to develop after the initial infection with HCV, so this screening test may miss a few newly-infected individuals. The EIA screening tests are very good (specific); if the test is positive the probability of having HCV infection is greater than 99 per cent.

Recombinant immunoblot assay (RIBA) is used to confirm the positive results of EIAs. RIBA is still useful to differentiate false positive results in the few individuals whose immune systems have eliminated the virus but still have antibodies left over from the resolved infection.

HCV contains RNA and therefore several tests are available to measure the amount of HCV RNA in a person’s blood. These tests are referred to as molecular tests because they examine the virus at the molecular level. A single negative test for RNA does not mean that there is no infection because the virus may appear in the blood intermittently or may exist in small amounts. Newer tests have helped by detecting smaller and smaller amounts of virus in the blood.

Testing for RNA is useful in determining whether or not a patient has circulating virus in the blood (viremia). Hence, it can be used to confirm that a positive EIA/ELISA truly reflects active HCV infection.

RNA testing also should be done in individuals who may have been recently exposed to HCV. HCV RNA testing is more sensitive than the conventional EIA testing. The reason for this greater sensitivity is that it may take a person several weeks after exposure to HCV to develop the antibodies, whereas HCV RNA becomes detectable one to three weeks after exposure.

Additionally, HCV RNA testing may be helpful to assess a patient’s response to treatment at certain time points during antiviral therapy.

Blood tests also have been developed to identify the HCV genotype. This information is used to help guide treatment.

Blood tests can tell the clinician whether HCV is present but cannot tell the level of liver damage that has occurred.

Here the best diagnostic exam is liver biopsy.  Liver biopsy allows the clinician to determine how much inflammation and scarring is present by examining a small sample of liver tissue. Liver biopsy gives useful information in the decision to initiate therapy. Significant liver damage is a risk factor for other conditions such as hepatocellular carcinoma and esophageal varices.

Liver biopsy may be recommended when the clinician is uncertain about whether to begin treatment or wishes to monitor the response within the liver to therapy.

It is possible to measure liver stiffness with transient elastography, a non-invasive test. Stiffer livers mean that advanced liver fibrosis may be present. However such tests do not completely replace the need for liver biopsy in routine clinical practice.

Patients with HCV infection should discuss treatment options with a physician who is experienced in treating the disease.

Individuals who should not be treated with antiviral therapy include those who are unable to comply with the treatment schedule, have reasons that may make treatment unsafe for example allergy to the medications, have received a solid organ transplant, are pregnant or unwilling to practice adequate contraception during treatment,  reversible serious untreated conditions such as unstable heart disease, uncontrolled high blood pressure, and untreated major depression.

Patients with unstable (decompensate) cirrhosis are at high risk for developing complications on medical treatments except in research settings.

Fundamentally, the decision regarding antiviral therapy in chronic HCV infection should be tailored to the individual patient with careful consideration of the risks and benefits.

All patients with HCV should be vaccinated against hepatitis B and hepatitis A. They also should be counseled on measures to prevent the spread of HCV and eliminating alcohol use. Finally, risk behaviors for HCV overlap with those of HIV, and all patients with HCV should be tested for HIV.

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