Can influenza A cause elevated liver function tests?

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Can Influenza A Cause Elevated Liver Function Tests?

Yes, influenza A infection commonly causes elevated liver function tests, particularly in severe disease, and these elevations are associated with worse clinical outcomes and higher mortality.

Pattern and Frequency of LFT Abnormalities

Influenza A causes deranged liver function tests in a substantial proportion of infected patients, with the pattern varying by disease severity:

  • In avian influenza A (H5N1), deranged LFTs occurred in 29-100% of pediatric cases and 80-100% of adult cases, with elevated ALT specifically documented in 14-100% of children and 60-100% of adults 1
  • In seasonal influenza, approximately 11-12% of pediatric patients with acute respiratory infections show elevated liver enzymes, with influenza B showing the highest rate at 24.4%, followed by other respiratory viruses 2
  • Comparative data shows abnormal liver tests (ALT or AST ≥40 IU/mL) are common in hospitalized influenza patients, with most elevations being mild to moderate 3

Clinical Significance and Prognostic Implications

The presence of elevated LFTs in influenza A infection carries important prognostic weight:

  • Mortality association: Deranged LFTs were associated with poorer prognosis in avian influenza H5N1, particularly when combined with lymphopenia 1
  • Severe elevations matter most: Death occurred mainly in patients with severe liver test abnormalities (>200 IU/L), affecting 38.7% of influenza patients with this degree of elevation 3
  • Independent predictor: In multivariate analysis controlling for age, sex, lymphopenia, and C-reactive protein, liver test abnormalities remained significantly associated with death (odds ratio 4.344; 95% CI 2.218-8.508) 3

Mechanisms of Liver Injury

Influenza A causes hepatic dysfunction through multiple pathways, not direct viral hepatotropism:

  • Systemic inflammation: The liver injury reflects disease severity and systemic inflammatory response rather than direct viral invasion of hepatocytes 3
  • Hypoxic hepatitis: In severe cases with septic shock and pneumonia, centrilobular hepatocyte necrosis can occur due to reduced hepatic oxygen supply, particularly in patients with pre-existing conditions like anemia or chronic renal failure 4
  • Hepatic decompensation: Patients with pre-existing cirrhosis can develop acute decompensation during influenza A infection, manifesting as ascites, hepatic encephalopathy, and peripheral edema, though this typically resolves within one month 5

Temporal Pattern

The timing of LFT elevation differs from other viral respiratory infections:

  • Earlier peak in influenza: The majority of influenza patients show transaminase peaks earlier during hospitalization compared to SARS-CoV-2 patients, though both infections show similar overall patterns 3
  • Onset timing: In severe cases, hepatic manifestations typically develop 2-4 days after respiratory symptoms begin 1

Clinical Management Considerations

When encountering elevated LFTs in influenza A patients:

  • Rule out alternative causes: Always check hepatitis B surface antigen and anti-hepatitis C virus antibody when LFTs are abnormal, as you would under normal circumstances 1
  • Monitor severity markers: Elevated LFTs correlate with other markers of severe disease including lymphopenia, thrombocytopenia, and hypoalbuminemia 1
  • Generally transient: Hepatic dysfunction is typically transient and does not require special treatment beyond supportive care 1
  • Consider complications: When liver function continues to deteriorate, consider complications such as myositis (especially when AST exceeds ALT), ischemia, cytokine release syndrome, and drug-induced liver injury 1

Critical Pitfalls to Avoid

  • Don't assume mild respiratory symptoms exclude severe hepatic involvement: Cases exist where hemodialysis patients with mild respiratory symptoms developed severe hepatitis and liver failure from influenza A 6
  • Don't delay antiviral treatment: Patients with severe illness may benefit from antiviral therapy even beyond 48 hours of symptom onset 1
  • Don't overlook pre-existing liver disease: Patients with cirrhosis or awaiting transplantation are at particular risk for hepatic decompensation and require close monitoring and vaccination 5

References

1
Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

6
Research

Severe liver failure due to influenza A infection in a hemodialysis patient.

Hemodialysis international. International Symposium on Home Hemodialysis, 2016

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Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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