How Hepatitis Is Diagnosed

Although hepatitis, inflammation of the liver caused by a virus, sometimes brings on obvious symptoms, a blood test usually is required to make a definitive diagnosis. This is because the symptoms of the disease if they even develop tend to be mild and to mimic those of the flu. Because hepatitis is caused by infection with one of five viruses, a blood test can detect the presence of either a specific hepatitis virus or antibodies to that virus produced by the immune system to ward it off.

When hepatitis becomes chronic—meaning the infection has persisted beyond six months and has begun to cause damage to the liver—more extensive tests may be done, including imaging tests and liver biopsy.

Symptoms that might prompt a doctor to suspect a patient has hepatitis include flu-like or gastrointestinal symptoms along with jaundice (yellowing of the skin or whites of the eyes, dark urine, or pale stools). In this case, he or she is likely to order a blood test, which is the most common way to definitively diagnose hepatitis.

Liver Enzyme Tests

The liver uses proteins called enzymes to help with essential functions. Normally it keeps tight control of these enzymes, but when the liver is damaged, enzymes can escape into the blood where they can be detected in a small sample of blood.

In general, testing for elevated liver enzymes is a solid approach to diagnosing hepatitis, but there is one drawback: Although the results can determine that there is liver damage, they can't reveal the cause of the damage—in other words, which hepatitis virus is behind the infection.

Antibody Tests

The immune system makes two types of antibodies specific to individual viruses: As soon as the body identifies a virus, it produces IgM antibodies to fight that specific virus. Toward the end of infection, the body produces IgG antibodies that also are specific to the virus but function to provide future immunity.

Tests exist for both IgM and IgG antibodies specific to three hepatitis viruses: hepatitis A (HAV), hepatitis B (HBV), and hepatitis C (HCV).

Direct Viral Measures

In addition to detecting antibodies for HBV and HCV, tests called polymerase chain reaction, or PCR, tests can be used to directly measure the amount of virus in the blood.

Although imaging tests cannot detect a viral infection of the liver, certain ones can reveal inflammation, changes in size, and tumors that can be consequences of chronic infection or liver disease caused by hepatitis.

• Abdominal ultrasound: This test can evaluate abnormalities in the liver and abdomen, and may also detect the fluid build-up in the abdomen, which can occur with liver failure. 
• Computerized Axial Tomography (CT): An abdominal CT scan can detect changes in the size and density of the liver and may visualize masses or signs of early cancer. 
• Magnetic Resonance Imaging (MRI): An MRI can pick up on abnormalities that suggest liver dysfunction or cancer. 

A liver biopsy is a section of tissue taken from the liver and evaluated under a microscope to look for identifying features disease.

The most common type of liver biopsy is called a percutaneous biopsy, which involves inserting a hollow needle through the abdomen into the liver through which a sample of tissue can be extracted.

This is an outpatient procedure, which means it doesn't require a hospital stay. Usually, the only anesthesia necessary is a local one to numb the area into which the needle will be inserted. However, a sedative can be used if necessary.

A Word From Verywell

Because the symptoms of hepatitis can be mild or mimic other diseases—if there are any symptoms at all—it can be tricky to diagnose. If you have any symptoms that you think might point to a liver problem—especially jaundice—see your doctor. A simple blood test may be all that's necessary to determine if you have any of the viral forms of hepatitis and if you should be treated.