Soluble CD25 as a Prognostic Biomarker for Pediatric Septic Shock and Its Comparison with Hemophagocytic Lymphohistiocytosis

Objectives: Identifying children at highest risk for deterioration during evaluation for septic shock in emergency department (ED) settings remains challenging. Soluble CD25 (sCD25), a hemophagocytic lymphohistiocytosis (HLH) diagnostic criterion, has been associated with sepsis mortality in ICU settings. This study aimed to determine whether sCD25 is associated with adverse outcomes in children undergoing initial septic shock evaluation in a pediatric ED. We also sought to compare sCD25 in patients with septic shock, infection without sepsis, and HLH. Results: Children with HLH demonstrated significantly higher sCD25 levels [25,800 pg/mL (IQR: 1,620–42,300)] compared with those with septic shock [5,200 pg/mL (IQR: 2,500–20,600)] or infection [5,500 pg/mL (IQR: 2,200–12,500)]. No statistical differences were observed between septic shock and infection groups; however, a subset of septic shock patients exhibited sCD25 elevations comparable to HLH patients. These patients experienced severe outcomes, including 100% PICU admission, 50% vasoactive support requirement, and prolonged hospitalization (16 days). Bloodstream infections were associated with the highest sCD25 levels. These findings suggest sCD25 elevation may be associated with adverse outcomes in children with septic shock. Larger studies are warranted to validate sCD25 as a prognostic marker for children with septic shock.