Diagnosing Hepatitis

While your physician has a number of tools to diagnose hepatitis, he or she will use some more than others. We'll be looking at the more common tests in this article.

Signs and Symptoms

In general, your doctor will ask questions about your symptoms such as what has bothered you, when you noticed it and how severe they have been. If they suspect hepatitis, he or she will ask specifically about flu-like or gastrointestinal symptoms. The doctor will then perform a physical exam and look for signs that might point to the cause of the problem such as an enlarged liver or yellowing of your eyes or skin. After meeting with you, your doctor will probably test some of your blood for any markers of liver dysfunction or inflammation such as the liver enzymes.

Liver Enzymes

An enzyme is a protein that assists in chemical reactions and there are lots of these proteins in the body that do different jobs. The liver uses some of these to help with its essential functions, such as building things up, breaking things down and disposing of various waste products.

Normally the liver keeps tight control of its enzymes, but when the liver is damaged, these enzymes can escape into the blood. Tests can determine if these enzymes are in the blood and tell how much is present. The three most common enzymes doctors use to test for liver damage are alanine aminotransaminase (ALT), aspartate aminotransferase (AST), and gamma glutamyl transaminase (GGT).

It's a good system but there is a big drawback. While liver enzymes can tell if there is liver damage, they can't tell the cause of the damage. If the doctor suspects a viral cause, he or she will order different blood tests that look for specific virus antibodies.

Antibody Tests

The body's immune system makes antibodies and they are specific to a particular virus. As soon as the body determines a viral infection, it starts producing IgM antibodies which target that specific virus. Later at the end of infection the body produces another type of antibody called IgG. This, too, is specific to the virus but it provides future immunity. Doctors can test the blood for IgM and IgG antibodies specific to hepatitis A or hepatitis B. For hepatitis C, the principle is the same but physicians test for different antibodies.

Direct Viral Measures

Once antibodies point to evidence of viral hepatitis, useful PCR tests for HBV and HCV can be sent which are direct measures of the amount of virus in the blood.

Advanced Tests

Usually, the diagnosis of hepatitis is made using a combination of tests. More advanced tests might include using imaging technology such as ultrasound, computerized axial tomography (CT) scans or magnetic resonance imaging (MRI), or a liver biopsy, where a doctor removes a small piece of the liver and sends it to a laboratory for further testing.