Liver Hepatitis C Diagnosis

Doctors use a variety of blood tests to diagnose different types of hepatitis, including hepatitis C. While some blood tests confirm or deny infection, others determine the amount of hepatitis C virus (HCV) in the body. Not all blood test results are 100 percent reliable, and you may be infected despite a negative test result. For that reason, doctors usually perform more than one analysis when diagnosing hepatitis C. If you’ve been exposed to situations in which HCV can be transmitted, you should be tested.

Liver Function Tests

Liver function tests evaluate liver enzyme levels in the bloodstream. High levels or abnormal ratios may indicate hepatitis C or another liver disorder, while low levels and normal ratios generally indicate normal liver function. Liver enzyme levels aren’t definitive in diagnosing hepatitis C, so your doctor may order more specific tests, depending on your results.

If you’ve been diagnosed with chronic HCV, your doctor may perform regular liver enzyme assessments to determine the progression of the disease and its effects on the liver, even in the absence of noticeable symptoms of hepatitis C.

Enzyme Immunoassay Tests

One of the early steps in diagnosing hepatitis C, an enzyme immunoassay test identifies the presence of antibodies manufactured by the immune system in response to the hepatitis C virus. A positive result may indicate an ongoing infection or a previous infection with no active virus. A negative result doesn’t rule out the possibility of HCV, however; it only indicates that the test didn’t detect HCV antibodies, which may not be detectable until weeks after infection.

A second test, called an HCV RNA test, can confirm or refute the result of the enzyme immunoassay test, although neither can classify the infection as acute or chronic or determine if the virus is active.

Polymerase Chain Reaction

A quantitative polymerase chain reaction test (PCR) measures the quantity of HCV particles in the bloodstream. This test can establish whether the virus is still active and indicate whether the viral load is high or low (undetectable). Since many people experience no symptoms of hepatitis C, a PCR test may be helpful in determining the length of a treatment program and monitoring a patient’s response to therapy. However, it doesn’t provide information about the degree or pattern of liver damage.

Liver Biopsy

One of the symptoms of hepatitis C (in its chronic form) is cirrhosis, a condition in which inflammation damages healthy liver tissue, replacing it with scar tissue. In order to assess the damage, your doctor may perform a liver biopsy, which involves introducing a small needle into the liver and removing a tiny sample of tissue. This tissue is then examined for signs of inflammation and scarring.

Types of Hepatitis C

Viral genotyping can determine which of the types of hepatitis C you have. The hepatitis C virus has six different major strains, with several additional sub-types. Knowing which of the types of hepatitis is causing the infection helps doctors determine how well the infection is responding to treatment.

Resources

Franciscus, A. (2006). Hepatitis C diagnostic tests. Retrieved September 28, 2010, from http://www.hcvadvocate.org/hepatitis/factsheets_pdf/diagnostic_FS.pdf.

Mayo Clinic. (n.d.). Hepatitis C. Retrieved September 28, 2010, from http://www.mayoclinic.com/health/hepatitis-c/DS00097.

National Digestive Diseases Information Clearinghouse. (2006). Chronic Hepatitis C: Current disease management. Retrieved September 28, 2010, from http://digestive.niddk.nih.gov/ddiseases/pubs/chronichepc/.