hepatic and biliary disorders
Hepatitis A
Diagnosis of Hepatitis A
Serologic testing In the Initial diagnosis of acute hepatitis , viral hepatitis should be differentiated from other disorders causing jaundice (see figure If acute viral hepatitis is suspected, the following tests are done to screen for hepatitis viruses A, B, and C: IgM antibody to HAV (IgM anti-HAV) Hepatitis B surface antigen (HBsAg) IgM antibody to hepatitis B core (IgM anti-HBc) Antibody to hepatitis C virus (anti-HCV) and hepatitis C RNA (HCV-RNA) If the IgM anti-HAV test is positive, acute hepatitis A is diagnosed. The IgG antibody to HAV (IgG anti-HAV) test is done (see table Diagnosis ) to help distinguish acute from prior infection. A positive IgG anti-HAV test suggests prior HAV infection or acquired immunity. There is no further testing for hepatitis A. HAVis present in serum only during acute infection and cannot be detected by clinically available tests. IgM antibodytypically develops early in the infection and peaks about 1 to 2 weeks after the development of jaundice. It diminishes within several weeks, followed by the development of protective IgG antibody (IgG anti-HAV), which persists usually for life. Thus, IgM antibody is a marker of acute infection, whereas IgG anti-HAV indicates only previous exposure to HAV and immunity to recurrent infection. Liver tests are needed if not previously done; they include serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase. Other tests should be done to evaluate liver function; they include serumalbumin, bilirubin, and prothrombin time/international normalized ratio (PT/INR). 