What laboratory tests should be requested for a patient suspected of having hepatitis?

Laboratory Testing for Suspected Hepatitis

For any patient with suspected hepatitis, order a comprehensive initial panel that includes: hepatitis A IgM antibody, hepatitis B surface antigen (HBsAg), hepatitis B core antibody IgM (anti-HBc IgM), hepatitis C antibody with reflex HCV RNA if positive, and hepatitis E IgM antibody—all tested simultaneously at presentation. 1

Core Hepatitis Panel (Order All Initially)

For Hepatitis A:

• HAV IgM antibody - This is the definitive marker for acute hepatitis A infection 2, 1

For Hepatitis B:

• HBsAg (Hepatitis B surface antigen) - Primary marker for active infection; positivity >6 months defines chronic infection 2, 1
• Anti-HBc IgM (IgM antibody to hepatitis B core antigen) - Distinguishes acute from chronic infection 2, 3
• Anti-HBc IgG - The IgG form should be checked as part of the standard panel; an isolated positive may indicate chronic HBV requiring quantitative HBV DNA testing 2

For Hepatitis C:

• Anti-HCV antibody - Initial screening test 2
• HCV RNA (qualitative or quantitative) - Must be ordered if anti-HCV is positive to confirm active viremia; use assay with lower limit of detection <15 IU/ml 2, 1
• Important caveat: Up to 20% of acute hepatitis C cases will be anti-HCV negative at initial presentation due to delayed seroconversion (5-10% haven't seroconverted yet, 5-10% remain negative even with prolonged follow-up) 2, 1

For Hepatitis E:

• HEV IgM antibody - Critical to test simultaneously with other hepatitis markers, as hepatitis E is now the most common cause of acute viral hepatitis in many developed countries 1
• HEV RNA by nucleic acid testing - Required for diagnosis in immunosuppressed patients 1
• Critical pitfall: Do NOT delay HEV testing until HAV, HBV, and HCV are negative—test all simultaneously, as 13% of presumed drug-induced liver injury cases are actually acute hepatitis E 1

Essential Liver Function Tests

• ALT and AST - To assess liver inflammation; ALT >2.5 times upper limit of normal is required for hepatitis C diagnosis 2, 1
• Total bilirubin - To evaluate severity of acute injury 1
• Alkaline phosphatase - Part of standard workup 2
• PT/INR, albumin - To assess synthetic liver function 2
• CBC with platelets - Complete blood count is part of standard evaluation 2

Additional Testing Based on Initial Results

If HBsAg is Positive:

• HBeAg and anti-HBe - Determines disease phase and viral replication status 3
• Quantitative HBV DNA - Essential for treatment decisions; levels ≥2,000 IU/mL in HBeAg-negative or ≥20,000 IU/mL in HBeAg-positive indicate active disease 3
• Anti-HDV (hepatitis delta antibody) - Mandatory testing, as HDV only infects in presence of HBV 3, 1

If Anti-HBc IgG is Isolated Positive (without HBsAg):

• Quantitative HBV DNA - Required to rule out occult HBV infection, especially critical before immunosuppressive therapy 3
• Anti-HBs (hepatitis B surface antibody) - Helps distinguish resolved infection from occult infection 3

If Anti-HCV is Positive:

• Quantitative HCV RNA - Confirms active viremia 2
• HCV genotype - Required if HCV RNA is positive for treatment planning 2

Mandatory Coinfection Screening

• HIV antibody/antigen - Test all hepatitis-positive patients, as coinfection accelerates liver disease progression 3
• Anti-HCV antibody - If not already done, test all HBV-positive patients 3
• Anti-HDV antibody - Required in all HBsAg-positive or anti-HBc IgM-positive patients, particularly those with injection drug use history or from endemic areas 1

Autoimmune Hepatitis Panel (If Viral Markers Negative)

• ANA (antinuclear antibody) 1
• SMA (smooth muscle antibody) 2, 1
• Anti-LKM-1 (anti-liver kidney microsomal antibody) 2, 1
• AMA (anti-mitochondrial antibody) 2, 1
• Serum immunoglobulins - Raised IgG suggests autoimmune hepatitis 2

Additional Metabolic/Genetic Testing

• Ferritin and transferrin saturation - Screen for hemochromatosis (transferrin saturation >45% is significant) 2
• AFP (alpha-fetoprotein) - Part of hepatocellular carcinoma surveillance in chronic liver disease 2

Critical Pitfalls to Avoid

Window Period in Hepatitis B: During the serologic window period, both HBsAg and anti-HBs may be negative—anti-HBc IgM will be the only positive marker during this time 1

Delayed HCV Seroconversion: If clinical suspicion is high but anti-HCV is negative, repeat testing in 12 and 24 weeks, as seroconversion can be delayed 2

Missing Hepatitis E: Always test for HEV simultaneously with other hepatitis markers in acute presentations—do not wait for other tests to return negative first 1

Occult HBV Before Immunosuppression: In patients with isolated anti-HBc IgG who are candidates for immunosuppressive therapy, HBV DNA testing is mandatory even if HBsAg-negative, as occult infection can reactivate 3