What are the typical liver function test findings in children with acute hepatitis A?

Liver Function Test Findings in Children with Acute Hepatitis A

In children with acute hepatitis A, expect marked elevations in serum aminotransferases (ALT and AST typically >1000 U/L during the acute phase), with ALT often exceeding AST, accompanied by elevated total and direct bilirubin, while other liver function parameters usually remain within normal ranges. 1, 2

Typical Aminotransferase Pattern

• Serum ALT and AST rise rapidly during the prodromal period, reaching peak levels that can exceed 1000 U/L, with both enzymes typically elevated to similar degrees. 2
• The aminotransferases then decrease by approximately 75% per week following peak levels. 2
• In the multicenter Korean study of 613 children with acute infectious diseases causing liver enzyme elevation, mean initial AST was 171.2 ± 274.1 IU/L and ALT was 194.9 ± 316.1 IU/L, though hepatitis A specifically tends toward higher peaks. 1

Bilirubin Elevation Pattern

• Serum bilirubin concentrations reach peak levels later than aminotransferases and decline less rapidly. 2
• The period of jaundice persists for less than 2 weeks in approximately 85% of cases. 2
• Children with atypical presentations have significantly higher total serum bilirubin (mean 13.7 ± 8.1 mg/dL) compared to those with typical presentation (7.2 ± 4.0 mg/dL). 3

Other Liver Function Parameters

• Despite marked aminotransferase elevations, other liver function tests (albumin, synthetic function markers) typically remain within normal range in uncomplicated acute hepatitis A. 1
• Prothrombin time remains normal in uncomplicated cases but becomes significantly prolonged (>90 seconds) in children progressing to acute liver failure. 4

Age-Related Considerations

• In young children, hepatitis A infections are usually subclinical or asymptomatic, meaning many cases never come to medical attention despite biochemical abnormalities. 5, 2
• The severity of illness and likelihood of symptomatic presentation with jaundice increases with age. 2
• Children with atypical presentations tend to be older (mean 7.7 ± 1.6 years) compared to those with typical presentation (6.5 ± 2.6 years). 3

Recovery Timeline

• Nearly all children with clinically apparent disease experience complete clinical recovery with restoration of normal serum bilirubin and aminotransferase values by 6 months. 2
• Older age is associated with better ALT recovery (odds ratio per month of age = 1.003), while multiple infection episodes predict slower recovery. 1

Red Flags Requiring Immediate Evaluation

• Prothrombin time prolongation >90 seconds is the most significant predictor of mortality and indicates progression to acute liver failure. 4
• Development of encephalopathy, coagulopathy not corrected by vitamin K, or hypoglycemia mandates immediate specialist consultation or emergency evaluation. 6
• In the Pakistani cohort, 36.7% of children with hepatitis A-related liver failure died, with prothrombin time being the most significant predictor of survival. 5

Atypical Presentations (14% of Cases)

• Approximately 15% of children with acute hepatitis A develop atypical manifestations including prolonged cholestasis (lasting >2 weeks), acute liver failure, relapse, ascites, or hematological complications. 3
• These atypical presentations are associated with older age and higher total serum bilirubin at presentation. 3
• Even in prolonged cholestasis cases, recovery is the rule and chronic hepatitis does not occur with hepatitis A. 2

Common Pitfall to Avoid

Do not assume that normal or mildly elevated liver enzymes exclude significant hepatitis A in young children, as the disease is frequently asymptomatic or subclinical in this age group despite active infection. 2 Conversely, in children presenting with marked aminotransferase elevations (>1000 U/L), hepatitis A should be strongly considered along with other viral causes including hepatitis E, cytomegalovirus, and Epstein-Barr virus. 7