Estimation of zinc level as a predictor of outcome of para-pneumonic effusion in children

Abstract Background Parapneumonic effusion (PPE) is a common and morbid complication of childhood pneumonia. Although zinc plays a key role in immune modulation and may influence disease course, its prognostic significance in PPE has not been well defined. Objective To assess serum zinc levels in children with PPE and evaluate their association with disease severity and clinical outcomes. Methods This cross-sectional study enrolled 63 children (1–13 years) with clinically and radiologically confirmed PPE admitted to Abo El Rish Children’s Hospital, Cairo University, between January and September 2024. Participants were classified as zinc-deficient (< 50 µg/dL; n = 18) or zinc-sufficient (≥ 50 µg/dL; n = 45). Demographic, clinical, laboratory, microbiological, and imaging data were collected, and outcomes compared between groups. Results Median serum zinc was 61.8 µg/dL (IQR: 48.05–114.8), with deficiency in 28.57% of patients. Groups did not differ significantly in age, sex, symptom duration, vital signs, hematologic indices, or most inflammatory markers, except for a higher second-hour ESR in the zinc-sufficient group ( p = 0.013). Blood cultures were positive in 5.6% of cases, and imaging findings were similar between groups. Clinical improvement was observed in 94.44% of zinc-deficient and 97.78% of zinc-sufficient patients. ROC analysis indicated that zinc ≥ 50 µg/dL predicted improvement with 72.13% sensitivity, 50% specificity, and an AUC of 0.836 ( p < 0.001). Conclusion Serum zinc showed no association with initial disease severity; however, concentrations ≥ 50 µg/dL were to be associated with positive outcomes, supporting its potential value as a prognostic marker in PPE.