A cost-effective diagnostic workup of patients with possible acute viral hepatitis is the most reasonable approach. Because 75% of cases of acute viral hepatitis result from infection with either HAV or HBV, the initial laboratory investigation should include serologic tests to exclude HAV or HBV. If the results of these studies are negative, further testing should be done to rule out acute HCV infection, which is less common. Serum HCV RNA is detectable 1 to 2 weeks after the onset of infection, whereas anti-HCV can be detected 8 to 10 weeks following infection with the virus. In clinically stable patients, waiting and checking the presence of antibodies to HCV may be plausible. Checking for HCV RNA by polymerase chain reaction in all patients is not cost-effective, unless there is a known history of blood exposure. Finally, not all acute hepatitis is viral. If the initial evaluation fails to show viral hepatitis, then other causes of hepatitis, such as alcoholic hepatitis, drug toxicity, autoimmune hepatitis, or Wilson’s disease, should be considered.
Hepatitis
Diagnostic Criteria for Chronic HBV Infection
Chronic HBV infection is a necroinflammatory disease of the liver caused by persistent infection with HBV, and can be categorized as hepatitis B e antigen (HBeAg) positive or negative. Inactive hepatitis B surface antigen (HBsAg) carriers have HBV infection of the liver without significant, ongoing necroinflammatory disease. HBV infection is resolved when there is no further virologic, biochemical, or histologic evidence of active viral infection or disease.
Typical Serologic Course of Hepatitis A Virus (HAV) Infection
Since both clinically and biochemically, acute hepatitis due to HAV cannot be distinguished from that due to the other hepatitis viruses, serologic tests are necessary for a virus-specific diagnosis.
Serologic Testing for the Diagnosis of Hepatitis B Virus (HBV) Infection
The antigens and antibodies associated with HBV infection include HBsAg (Australia antigen) and antibody to HBsAg (anti-HBs), hepatitis B core antigen (HBcAg) and antibody to HBcAg (anti-HBc), and hepatitis B e antigen (HBeAg) and antibody to HBeAg (anti-HBe). At least one serologic marker is present during the different phases of HBV infection.
Diagnostic Criteria for Autoimmune Hepatitis (AIH)
Autoimmune hepatitis (AIH) is characterized by inflammatory liver histology, circulating non-organ-specific autoantibodies, and increased levels of immunoglobulin (Ig) G in the absence of a known etiology.