How do I interpret hepatitis lab results?

How to Read and Interpret Hepatitis Lab Results

The most effective way to interpret hepatitis lab results is to understand the specific serological markers and their patterns, which indicate different stages of infection, immunity status, and disease severity.

Understanding Serological Markers for Hepatitis B

• A complete hepatitis B panel should include HBsAg (hepatitis B surface antigen), anti-HBs (antibody to HBsAg), anti-HBc IgM and IgG (antibodies to hepatitis B core antigen), HBeAg (hepatitis B e-antigen), and anti-HBe (antibody to HBeAg) 1
• These markers help evaluate viral replication status and infectivity 1

Interpretation of HBV Test Results:

• HBsAg positive for >6 months + HBV DNA >105 copies/mL + elevated ALT/AST: Indicates chronic hepatitis B 2
• HBsAg positive for >6 months + HBeAg negative + anti-HBe positive + HBV DNA <105 copies/mL + normal ALT/AST: Indicates inactive HBsAg carrier state 2
• HBsAg negative + positive anti-HBs + negative anti-HBc: Indicates successful vaccination 3
• HBsAg negative + positive anti-HBs + positive anti-HBc: Indicates resolved HBV infection 3

Understanding Serological Markers for Autoimmune Hepatitis

• Initial serological battery should include assessments for antinuclear antibodies (ANA), smooth muscle antibodies (SMA), antibodies to liver/kidney microsome type 1 (LKM-1), and antimitochondrial antibodies (AMA) 2
• If conventional tests are negative but autoimmune hepatitis is suspected, test for antibodies to actin (F-actin), soluble liver antigen/liver pancreas (SLA/LP), liver cytosol type 1 (LC-1), and perinuclear anti-neutrophil cytoplasmic antibodies (pANCA) 2

Liver Function Tests Interpretation

• A comprehensive liver profile should include transaminases (ALT/AST), bilirubin, alkaline phosphatase, GGT, prothrombin time, albumin, and platelet count 1
• Hepatocellular pattern: Predominant elevation of transaminases (ALT/AST) over alkaline phosphatase 1
• Cholestatic pattern: Predominant elevation of alkaline phosphatase and GGT over transaminases 1
• Advanced liver disease: Presence of thrombocytopenia, hypoalbuminemia, and prolonged prothrombin time 1

Non-Invasive Assessment of Liver Fibrosis

• Transient elastography (TE) is superior to serum biomarkers for diagnosing cirrhosis in hepatitis patients 2
• TE <6 kPa with normal ALT: Indicates no significant fibrosis 2
• TE >9 kPa with normal ALT or >12 kPa with elevated ALT: Suggests severe fibrosis/cirrhosis 2
• TE between 6-9 kPa (normal ALT) or 6-12 kPa (elevated ALT): Considered a "grey area" requiring additional assessment 2

Algorithm for Interpreting Hepatitis Lab Results

1. Identify the type of hepatitis based on serological markers 4, 1
2. Assess disease activity using liver enzymes (ALT/AST) 1
3. Evaluate liver function using albumin, bilirubin, and prothrombin time 1
4. Determine fibrosis stage using non-invasive tests like transient elastography 2
5. Monitor for complications in advanced disease 4

Common Pitfalls to Avoid

• Using incomplete hepatitis panels that miss critical markers 3
• Misinterpreting normal transaminase levels as absence of significant liver disease 1
• Failing to consider the impact of ALT flares on transient elastography results in chronic hepatitis B 2
• Using diagnosis codes for hepatitis infection when the patient only has positive antibodies from vaccination 3
• Relying solely on the magnitude of transaminase elevation to determine disease severity 1

When to Consider Additional Testing

• When initial serological markers are inconclusive 2
• For patients with risk factors but negative initial screening 4
• For staging of liver disease to guide management decisions 2
• For monitoring treatment response and disease progression 4

Remember that interpreting hepatitis lab results requires understanding the clinical context, risk factors, and the pattern of abnormalities across multiple tests 4, 1.