Diagnostic Threshold of Immature Granulocytes in Pediatric Infections

Abstract

Objectives: This study aimed to assess the optimal cutoff and the diagnostic utility of IG in common pediatric infections.

Methodology: This case-control study included children aged 1–17 years presenting with suspected infection or sepsis between December 2024 and July 2025. Clinical and laboratory parameters (WBC, ANC, IG%, and absolute IG count) were recorded within 24 hours of presentation and compared with age-matched non-infected controls. Receiver Operating Characteristic (ROC) curve analysis was performed to evaluate diagnostic performance and calculate the area under the curve (AUC).

Results: A total of 150 patients (85 males, 65 females) with a mean age of 5.74 ± 4.59 years were included. Over 80% had gastrointestinal or respiratory infections. Compared with controls, patients showed significantly higher WBC and ANC (p < 0.001), IG% (0.91 ± 1.31 vs 0.22 ± 0.09; p = 0.001), and absolute IG count (0.13 ± 0.26 vs 0.02 ± 0.01 ×10?/L; p < 0.001). An IG% cutoff >0.25 yielded 82.0% sensitivity (95% CI 75.1–87.3) and 68.0% specificity (95% CI 60.2–74.9). Multivariable analysis confirmed IG% as an independent predictor of infection (p < 0.001).

Conclusion: IG% is a useful early biomarker that can be used in conjunction with traditional leukocyte indices (WBC and ANC) to detect pediatric infections, demonstrating improved overall diagnostic accuracy and facilitating timely clinical decision-making.