Acute hepatitis may be caused by hepatotropic viruses such as hepatitis A virus (HAV; most common cause of acute hepatitis), B, C, D, or E, as well as systemic viruses such as Epstein-Barr virus or herpes simplex. As well, acute hepatitis can be caused by drugs and toxins. Microscopically, patients with acute hepatitis have diffuse hepatocyte injury with ballooning and lymphocyte-mediated apoptosis. Severity may be anywhere in a wide range from mild (may be subclinical) to severe and fatal.
Chronic hepatitis is caused by hepatitis C virus, hepatitis B, and hepatitis G (B + D). Genetic factors include [[Wilson's disease, α1 antitrypsin deficiency. Other causes include autoimmune hepatitis and drugs and toxins, in addition to which there is the idiopathic category. Hepatitis C virus (HCV) is the most common cause of chronic viral hepatitis, and the primary indication for liver transplants. Pathological features include diffuse hepatocyte injury with ballooning and lymphocyte-mediated apoptosis, chronic inflammation, fibrosis and cirrhosis. Because there are significant differences in clinical course, treatment, and prognosis depending on the cause, a biopsy is carried out. Liver biopsies are done to determine etiology, detect or exclude other diseases, determine degree of necroinflammatory activity (grade), determine amount of fibrosis (stage), and evaluate the effects of treatment.
There may also be autoimmune hepatitis.
For the viral hepatitis B, you would test for core Hep B and surface antigen. Also, one would ask for Immunoglobulin M and Immunoglobulin G, which would be helpful in determining chronic or acute states of the hepatitis.