What blood work is required for the diagnosis and management of autoimmune hepatitis?

Blood Work Required for Diagnosis and Management of Autoimmune Hepatitis

The essential blood work for diagnosis of autoimmune hepatitis (AIH) includes liver function tests, immunoglobulin G levels, and autoantibody testing (ANA, SMA, anti-LKM1, and anti-LC1), along with tests to exclude viral hepatitis and other liver diseases. 1

Initial Diagnostic Blood Work

Core Laboratory Tests

• Liver Function Tests:

  • Serum AST and ALT (typically elevated, often >5 times upper limit of normal in moderate-severe cases)
  • Alkaline phosphatase (ALP)
  • Total bilirubin
  • Albumin
  • Prothrombin time/INR

• Immunological Markers:

  • Serum total IgG or γ-globulin levels (elevated >1.5-2 times upper limit of normal)
  • Autoantibodies:
    • Conventional panel (first-line testing):
      • Antinuclear antibodies (ANA)
      • Smooth muscle antibodies (SMA)
      • Anti-liver/kidney microsome type 1 (anti-LKM1)
      • Anti-liver cytosol type 1 (anti-LC1)

• Tests to Exclude Other Causes:

  • Viral hepatitis markers (HBV, HCV)
  • Ceruloplasmin, copper studies (Wilson's disease)
  • Alpha-1 antitrypsin level
  • Iron studies (ferritin, transferrin saturation)

Additional Serological Testing

If conventional autoantibodies are negative but AIH is still suspected, additional testing should include 1:

• Anti-soluble liver antigen/liver pancreas (anti-SLA/LP)
• Atypical perinuclear anti-neutrophil cytoplasmic antibodies (pANCA)
• Anti-actin antibodies (F-actin)
• Anti-mitochondrial antibodies (AMA) to exclude PBC

Diagnostic Patterns and Interpretation

Type 1 AIH (80% of cases)

• Positive ANA and/or SMA
• Elevated IgG levels

Type 2 AIH (more common in children)

• Positive anti-LKM1 and/or anti-LC1
• Elevated IgG levels (except IgA may be reduced)

Seronegative AIH

• Negative for conventional autoantibodies
• May be positive for anti-SLA/LP or atypical pANCA
• Diagnosis relies more heavily on histology and exclusion of other causes

Blood Work for Disease Monitoring

• Routine Monitoring:

  • Liver enzymes (AST, ALT)
  • Total bilirubin
  • Albumin
  • Complete blood count (to monitor for medication side effects)
  • IgG levels (to assess immunological activity)

• Treatment Monitoring:

  • For patients on azathioprine: complete blood count, liver enzymes
  • For patients on steroids: glucose, electrolytes, blood pressure

Special Considerations

• In patients with AIH and multiple endocrine disorders, testing for APECED syndrome should be considered through AIRE gene mutation analysis 1

• In children and adults with both AIH and inflammatory bowel disease, cholangiographic studies should be performed to exclude PSC 1

• Diagnostic scoring systems (simplified or revised original) should be applied in diagnostically challenging cases with few or atypical findings 1

Pitfalls to Avoid

1. Relying solely on autoantibody testing - Up to 10-15% of AIH patients may be seronegative for conventional antibodies

2. Failing to exclude viral hepatitis - This is essential before confirming AIH diagnosis

3. Not considering ethnic variations - Disease presentation varies among ethnic groups, which may affect laboratory findings 1

4. Overlooking type 2 AIH - Anti-LKM1 antibodies should be routinely tested to avoid missing this diagnosis, especially in children 1

5. Inadequate follow-up - Even apparently resolving cases require monitoring as severe relapse may occur in up to 70% of initially asymptomatic patients 1

By following this comprehensive blood work approach, clinicians can effectively diagnose AIH and monitor disease activity and treatment response, ultimately improving patient outcomes through early intervention.