What laboratory tests should be ordered to evaluate acute hepatitis?

Laboratory Testing for Acute Hepatitis

For acute hepatitis evaluation, order a comprehensive viral hepatitis panel (HAV IgM, HBsAg, anti-HBc IgM, anti-HCV with confirmatory HCV RNA, anti-HEV IgM), complete hepatic panel (AST, ALT, alkaline phosphatase, total and direct bilirubin, albumin, INR), complete blood count, and abdominal ultrasound as the initial workup. 1

Core Laboratory Panel

The 2025 British Society of Gastroenterology guidelines provide the most current framework for acute hepatitis workup 1:

Viral Serology (All Cases)

• HBV markers: HBsAg, anti-HBc (IgM and total), anti-HBs
• HCV antibody with reflex to HCV RNA if positive (antibodies may be absent in acute HCV, requiring direct RNA testing)
• HIV antibody (affects management and prognosis)

Additional Viral Testing for Acute Icteric Presentations

• HAV: anti-HAV IgM
• HEV: anti-HEV IgM and HEV RNA (increasingly common cause of acute hepatitis) 2
• EBV: VCA-IgM, EA-D antibody, EBNA antibody, EBV quantitative PCR 3
• CMV: CMV IgG antibody, CMV quantitative PCR 3

Critical caveat: Spurious low-level reactivity for HEV, EBV, or CMV IgM can occur in autoimmune hepatitis; viral PCR testing should confirm true infection 1

Biochemical Liver Assessment

• Transaminases: AST and ALT (elevations >1000 U/L suggest acute viral hepatitis, drug-induced liver injury, or ischemic hepatitis) 4
• Cholestatic markers: Alkaline phosphatase, GGT
• Synthetic function: Total and direct bilirubin, albumin, prothrombin time/INR
• Complete blood count with platelets

Metabolic/Genetic Screening

For acute presentations, standard screening tests have limitations as ferritin, ceruloplasmin, and α1-antitrypsin are acute phase reactants 1:

• Wilson's disease (especially in children/young adults <40 years):

  • Ceruloplasmin (though unreliable in acute inflammation)
  • 24-hour urinary copper
  • Slit lamp examination for Kayser-Fleischer rings
  • Consider genetic testing and liver biopsy 5, 3
  • Look for AST/ALT ratio >2.2, ALP/bilirubin ratio <4, Coombs-negative hemolysis

• Hemochromatosis: Ferritin, transferrin saturation, ± HFE genotyping 1

• α1-antitrypsin deficiency: α1-antitrypsin level and phenotype

Autoimmune Markers

• Serum IgG (elevated in autoimmune hepatitis)
• Autoantibodies via immunofluorescence:
  • ANA (antinuclear antibody)
  • ASMA (anti-smooth muscle antibody)
  • AMA (anti-mitochondrial antibody) - present in ~10% of AIH
  • Anti-LKM-1 (liver-kidney microsomal)

If initial antibodies negative, add: anti-SLA/LP, anti-LC-1, pANCA 1

Imaging

• Abdominal ultrasound (all patients) to assess:

  • Liver parenchyma and chronic disease features
  • Bile duct dilation
  • Portal hypertension signs
  • Hepatic steatosis

• MRCP if jaundice, rigors, or markedly elevated alkaline phosphatase to exclude biliary obstruction 1

Special Populations

Immunocompromised Patients

Add testing for 1:

• Herpes simplex virus (HSV 1,2,6): IgM antibodies, qualitative PCR
• Varicella zoster virus: IgM antibodies, qualitative PCR
• Consider adenovirus in children

Pregnant Women or Third Trimester

• HEV is particularly severe in pregnancy 6
• Consider HSV hepatitis (skin lesions present in only 50% of cases) 6
• Liver biopsy helpful for HSV diagnosis; treat with acyclovir if suspected 6

Recent Travel to Endemic Areas

• HEV testing mandatory (Russia, Pakistan, Mexico, India) 6
• Consider region-specific pathogens

Pattern Recognition for Differential Diagnosis

Hepatocellular Pattern (ALT/AST >> Alkaline Phosphatase)

ALT >1000 U/L suggests:

• Acute viral hepatitis (HAV, HBV, HCV, HEV)
• Drug-induced liver injury
• Ischemic hepatitis
• HSV/VZV hepatitis 3
• Autoimmune hepatitis flare

Cholestatic Pattern (Alkaline Phosphatase >> ALT/AST)

• Primary biliary cholangitis (check AMA)
• Primary sclerosing cholangitis (MRCP needed)
• Biliary obstruction

Mixed Pattern

• Drug-induced liver injury (check R ratio: ALT/ULN ÷ ALP/ULN)
• Autoimmune hepatitis with cholestatic features

Critical Diagnostic Pitfalls

1. Normal transaminases do NOT exclude acute hepatitis: 97.2% of acute viral hepatitis cases have elevated transaminases, but 2.8% do not 7. However, patients with normal transaminases and positive serology often have remote infection history.

2. Anti-HCV antibody timing: Up to 20% of acute HCV cases are antibody-negative initially; 5-10% never seroconvert. HCV RNA testing is essential for diagnosis 1, 6.

3. Acute phase reactants: Ceruloplasmin, ferritin, and α1-antitrypsin levels are unreliable in acute inflammation. For Wilson's disease in acute presentations, rely on 24-hour urinary copper, slit lamp exam, and clinical scoring systems 1, 5.

4. Drug history: Obtain detailed history of ALL medications including over-the-counter, herbals, and supplements taken in the past year 6, 4. Many cases of "acute hepatitis" are drug-induced liver injury.

5. HBV reactivation: Check anti-HBc in all patients, as HBV reactivation can occur in anti-HBc positive/HBsAg negative patients receiving immunosuppression 3.

When to Proceed to Liver Biopsy

Consider biopsy when 1:

• Diagnosis remains uncertain after serologic/imaging workup
• Multiple potential diagnoses exist
• Staging required for treatment decisions
• Suspected HSV hepatitis (diagnostic) 6
• Suspected Wilson's disease with equivocal biochemical tests 5

Do not perform biopsy if: Severe coagulopathy present without correction, or non-invasive workup strongly suggests a specific diagnosis with clear management pathway.