Hepatitis - Autoimmune Hepatitis

Diagnosis

Doctors diagnose hepatitis based on a physical examination and the results of blood tests. In addition to specific tests for hepatitis antibodies, doctors will order other types of blood tests to evaluate liver function.

Specific Tests for Hepatitis A

Blood tests are used to identify IgM anti-HAV antibodies, substances that the body produces to fight hepatitis A infection.

Specific Tests for Hepatitis B

There are many different blood tests for detecting the hepatitis B virus. Standard tests include:

• Hepatitis B surface antigen (HBsAg). A positive result indicates active infection, either acute or chronic.
• Antibody to HBsAg (Anti-HBs). A positive result indicates immunity to hepatitis B either from having been infected with the virus in the past or having had received the vaccine.
• Antibody to hepatitis B core antigen (Anti-HBc). A positive result indicates either recent infection or previous infection.
• Hepatitis B envelope antigen (HBeAg) indicates that someone with a chronic infection is actively contagious.
• Antibody to HBeAg (Anti-HBeAg) usually indicates succesful treatment of chronic hepatitis.
• Hepatitis B DNA (HBV DNA) detects hepatitis B viral genetic material. It can detect an active HBV infection. It is primarily used to monitor response to antiviral treatment in patients with chronic hepatitis B.

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Specific Tests for Hepatitis C

Tests to Identify the Virus. The standard first test for diagnosing hepatitis C is an enzyme immunoassay (EIA), which is used to test for hepatitis C antibodies. Antibodies can usually be detected by EIA 4 - 10 weeks after infection.

Tests to Identify Genetic Types and Viral Load. Additional tests called hepatitis C virus RNA assays may be used to confirm the diagnosis. They use a polymerase chain reaction (PCR) to detect the RNA (the genetic material) of the virus. Such tests should be used if EIA results show positive HCV antibody and may be performed if there is some doubt about a diagnosis but the doctor still believes the virus is present. HCV RNA can be detected through blood tests as early as 2 - 3 weeks after infection.