Is Calprotectin a Reliable Marker in Surgical ICU Settings? A Clinical Evaluation of Its Role in Sepsis and Mortality Prediction

Ebru Aladağ¹Muhammed Emin Zora²Yücel Gultekin^3*Soycan Mızrak⁴

• ¹Department of Anesthesiology and Reanimation, Faculty of Medicine, Alanya Alaaddin Keykubat University, Alanya, Turkey, Alanya, Türkiye
• ²Department of Anesthesiology and Reanimation, Faculty of Medicine, Uşak University, Uşak, Turkey, Uşak, Türkiye
• ³Aydın Adnan Menderes University Faculty of Medicine, Department of General Surgery, Intensive Care Unit, Aydın, Türkiye
• ⁴Department of Medical Biochemistry, Faculty of Medicine, Uşak University, Uşak, Turkey, Uşak, Türkiye

Background Calprotectin, a neutrophil-derived protein, has emerged as a potential biomarker for inflammation and infection. This study evaluated the utility of serum calprotectin levels in diagnosing sepsis and predicting mortality in surgical intensive care unit (ICU) patients. Methods This prospective observational study included 124 patients admitted to the surgical ICU at Uşak Training and Research Hospital between 2022 and 2024. Data on demographics, serum calprotectin, CRP, PCT, lactate levels, and clinical scores (SOFA, APACHE II) were collected. ROC analysis was used for predictive accuracy; Spearman and Pearson correlation coefficients assessed associations. Results No significant associations were found between serum calprotectin and SOFA/APACHE II scores, CRP, or lactate. However, calprotectin correlated positively with PCT in sepsis (r = 0.428, p = 0.002) negatively in postoperative subgroups (r = –0.48, p < 0.001). Calprotectin showed poor prognostic accuracy (AUC = 0.472). Mortality was significantly associated with high CRP and severity scores, but not with calprotectin levels. Conclusion Calprotectin alone lacks sufficient diagnostic or prognostic power for sepsis in surgical ICU patients. It may serve as a complementary marker alongside PCT in specific subgroups.