Hepatitis

Hepatitis, Autoimmune

Laboratory Evaluation of Hepatitis

• Hepatitis can be viral or non viral, acute or chronic (>6 mo)
• evaluation should be efficient and systematic

Stepwise evaulation

• CBC+diff, ALT, AST, Bili, GGT, (Alk Ph are difficult to interpret in children), PT. Mild ALT and AST elevation does not always predict the severity of the disease. PT is the most useful indicator of the liver synthetic function
• four serologic tests for viral hepatitis should be performed first:
  • HAV-IgM: immunoglobulin M (IgM) anti-hepatitis A virus
  • HbsAg: hepatitis B surface antigen
  • HBc-IgM: IgM anti-hepatitis B core
  • HCV: anti-hepatitis C virus
• If these tests are negative, other viral causes should be considered, including EBV and CMV, TORCH.
• If no viral cause can be identified, nonviral causes of acute and chronic hepatitis should be excluded:
  • bil atresia in neonates
  • Wilson disease (ceruloplasmine and urine 24h copper)
  • AAD (Alpha 1 antitrypsine level and protease inhibitor phenotyping)
  • CF (sweat test)
  • tyrosinemia (urinary succinyl acetone)
  • autoimmune hepatitis (in case of hypergammaglobulinemia)]
• Evaluate for hepatitis D in cases of + hep B

Ddx

• Acute hepatitis A: positive IgM anti-HAV. If positive IgG anti-HAV, in the absence of IgM= resolved hepatitis A infection with lasting immunity
• Both acute and chronic hepatitis B infections are diagnosed by the presence of HBsAg. HBsAg positivity warrants investigation of hepatitis D (delta hepatitis) coinfection or superinfection, as defined by the presence of IgM anti-HDV. Hepatitis D can occur only in the presence of HBsAg positivity.
• Acute hepatitis B infection: always positive IgM anti-HBc.
• Resolving infection or chronic hepatitis B: IgG anti-HBc positivity.
• Acute viral replication and high infectivity: HBeAg
• When viral replication ceases: Anti-HBe appears.
• Resolved hepatitis B and lasting immunity either from infection or immunization: anti-HBs.
• Hepatitis C is associated with the detection of anti-HCV. It should be later confirmed by PCR for HCV RNA