Purpose: Elevated transaminases have been associated with increased severity in adult influenza cases, but data in the pediatric population are limited. This study aims to evaluate the prevalence, clinical characteristics and prognostic value of elevated transaminases in children hospitalized for influenza.

Methods: A multicentre retrospective cohort study was conducted on 543 children hospitalized for acute viral respiratory infections. Demographic, clinical, biochemical, radiological features, and outcome were collected and analyzed, comparing children with influenza to those with other respiratory viruses. The association between elevated transaminases and clinical severity, complications, and intensive care unit (ICU) admission was assessed.

Results: Among 543 children, 127 (23.4%) had laboratory-confirmed influenza, with 24.4% showing elevated transaminases versus 7.2% in noninfluenza infections (p < 0.001). Influenza B was associated with a higher prevalence of hypertransaminasemia (40%) than influenza A (20.6%, p = 0.042). Asthenia, myalgia, and hypovolemic shock were more common in the elevated transaminase group (p < 0.05). Biochemical markers indicated muscular rather than hepatic origin of hypertransaminasemia. Elevated transaminases correlated with length of hospital stay (10.2 vs. 5.8 days, p < 0.001), ICU admission (OR 4.4, p = 0.035), high-flow oxygen need (OR 4.6, p = 0.005), and intravenous fluids (OR 6.2, p = 0.001). Two deaths occurred, both in the elevated transaminase group.

Conclusion: Elevated transaminases occur in one fourth of children hospitalized for influenza and are associated with more severe disease, systemic complications, and worse outcomes. The findings suggest that transaminase elevation reflects systemic and muscular involvement rather than primary liver injury. Monitoring transaminases provides an early, easy marker to identify children at risk of severe influenza.