The diagnostic and prognostic role of calprotectin levels in intensive care unit patients with sepsis: A prospective study

Background Early diagnosis of sepsis enables timely and appropriate treatment and reduces sepsis-related morbidity and mortality. However differentiating sepsis from noninfectious conditions and making a rapid diagnosis are difficult. Thus, reliable biomarkers with high sensitivity and specificity are needed for its early diagnosis and treatment. We evaluated the role of calprotectin (CLP) in the diagnosis of sepsis and antimicrobial treatment monitoring as well as its relationship with mortality. Methods This prospective study included 36 patients diagnosed with sepsis at Afyonkarahisar Health Sciences University Hospital between 2023 and 2024. Control group 1 comprise trauma patients meeting the systemic inflammatory response syndrome criteria but without an infectious focus, whereas control group 2 included healthy volunteers. The patients’ white blood cell (WBC) count, procalcitonin (PCT), C-reactive protein (CRP), lactate, and CLP levels, Acute Physiology and Chronic Health Evaluation (APACHE) II and Sequential Organ Failure Assessment (SOFA) scores, as well as neutrophil/lymphocyte ratio were monitored. In the study group, these parameters were measured on days 1, 3, 5, 7, and 10 after diagnosis and recorded, whereas in control groups 1 and 2, they were measured only during admission. The obtained data were statistically analyzed and compared. Results The CRP and PCT levels, WBC count, and neutrophil/lymphocyte ratio on day 1 were significantly different among the groups (p < 0.05), whereas the CLP level di not (p > 0.05). In the survivors, the SOFA and APACHE II scores and CRP, PCT, and lactate levels significantly decreased during the 10-day follow-up, but the CLP level remained unchanged (p > 0.05). In the study group, no significant association was found between CLP and CRP, PCT, and WBC (p > 0.05). In the receiver-operating characteristic analysis, comparing the mean CLP levels in the control groups with the values at the time of diagnosis in the study group, the cut-off value for sepsis diagnosis was 44.02 ng/L, with sensitivity and specificity of 52.8%. Conclusion The serum CLP level is not a sufficient standalone biomarker for differentiating sepsis from other inflammatory conditions. Given that serum CLP is influenced by numerous factors, it may not be an ideal biomarker for diagnosing sepsis and predicting mortality.