Tests can accurately diagnose whether you've been infected. Your health care provider may perform a physical exam to see if you have an enlarged and tender liver. Blood tests can detect the presence of hepatitis by measuring:
Bilirubin - Normally, your liver metabolizes this residue of worn-out red blood cells, and you excrete it in your urine. Hepatitis interferes with your liver's ability to metabolize bilirubin, leading to higher levels in your blood.
Enzyme levels - Your doctor may also look for elevated blood levels of enzymes known as aminotransferases, which are released when your liver is damaged.
If tests confirm the presence of hepatitis, your health care provider may still need to take another blood test called a radioimmunoassay to pinpoint the exact type of hepatitis you have. This test identifies:
Antibodies your immune system has formed in response to the presence of antigens
Proteins that are unique to a particular virus
Antibodies may not appear for weeks or even months after you develop hepatitis, so having the test too soon may give a false-negative result. In addition, you continue to have antibodies even after you recover. For that reason, the presence of some antibodies doesn't necessarily indicate an active infection.