Prognostic significance of serum apelin-13 and galectin-3 concentrations as potential indicators of severity and mortality in pediatric acute respiratory distress syndrome

BACKGROUND: The predictive and prognostic significance of apelin and galectin-3 as biomarkers in pediatric acute respiratory distress syndrome (PARDS) and lung injury has remained limited. This study examined the association between serum apelin-13 and galectin-3 levels, PARDS severity, and patient outcomes. METHODS: The study included children aged 1 month to 18 years diagnosed with PARDS on admission to a pediatric intensive care unit, alongside age- and sex-matched outpatient controls. PARDS was diagnosed and classified by severity according to Second Pediatric Acute Lung Injury Consensus Conference (PALICC-2) guidelines, based on oxygenation indices for non-invasive and invasive ventilation. Exclusion criteria included prior transplants, chronic lung disease, cyanotic congenital heart disease, prolonged ventilation, and other major conditions. After informed parental consent, 3 mL of peripheral venous blood was collected from all participants. Serum samples for apelin-13 and galectin-3 were stored at -80°C and analyzed using commercial enzyme-linked immunosorbent assay (ELISA) kits. Demographic, clinical, and laboratory data were systematically recorded for analysis. RESULTS: The study and control groups were comparable in age and gender. Patients had significantly lower hemoglobin, hematocrit, red blood cell, calcium, and phosphorus levels, and higher neutrophil counts, C-reactive protein, and liver enzymes. Apelin-13 levels did not differ significantly between groups, wheras median galectin-3 levels were significantly higher in patients (p=0.003). Apelin-13 levels were significantly lower and galectin-3 levels significantly higher with increasing PARDS severity. Severe PARDS was associated with lower PaO2/FiO2 ratios, arterial pH, and higher ventilator pressures. Mortality was 36.4% in severe and 22.7% in moderate PARDS. Serum galectin-3 level was the sole independent predictor of mortality (OR: 1.20, 95% CI 1.02-1.39, p=0.02). CONCLUSION: Although the apelin/APJ system's role in acute lung injury is known, its diagnostic and prognostic value in PARDS requires further study. Galectin-3 levels correlate with disease severity and outcomes, highlighting the need for larger, age- and phenotype-homogenized studies to confirm its role as an independent mortality predictor.