Retrospective analysis of the correlation between pathological disease activity severity and laboratory parameters in inflammatory bowel disease patients

Introduction and Objective: Inflammatory bowel diseases (IBD), mainly comprising ulcerative colitis (UC) and Crohn's disease (CD), are chronic immune-mediated inflammatory disorders. In recent years, treatment strategies have shifted beyond clinical remission toward endoscopic and histological healing as key therapeutic targets. Although histological activity is a strong predictor of disease course and prognosis, its assessment requires invasive procedures such as colonoscopy and biopsy, limiting its routine clinical use. Therefore, identifying non-invasive and easily accessible laboratory parameters that reflect histological activity is of clinical importance. This study aimed to retrospectively evaluate the correlation between histopathological disease activity and hematological and biochemical laboratory parameters in patients with inflammatory bowel disease. Materials and Methods: This retrospective study included adult patients with UC and CD who were followed at the Gastroenterology Clinic of Manisa Celal Bayar University Faculty of Medicine between January 2020 and June 2025 and underwent colonoscopy with histopathological evaluation. Histological activity was assessed using the Nancy Histological Index in UC patients and the Global Histologic Activity Score (GHAS) in CD patients. Demographic characteristics, clinical data, cytomegalovirus (CMV) status, and laboratory parameters obtained within ±4 weeks of biopsy (including hemoglobin, mean corpuscular volume, platelet count, C-reactive protein, albumin, neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio, systemic immune-inflammation index, and other hematological markers) were recorded. Appropriate parametric or non-parametric tests and Spearman correlation analysis were used for statistical evaluation. Results: Significant differences in laboratory parameters were observed according to the degree of histological activity. In the ulcerative colitis group, Nancy histological activity scores showed significant correlations particularly with C-reactive protein, albumin, and certain hematological inflammatory indices. In the Crohn's disease group, GHAS demonstrated significant correlations with selected laboratory parameters. However, the ability of individual laboratory markers to accurately reflect histological activity was limited, and heterogeneity was observed among patient groups. Conclusion: This study demonstrates that certain routine hematological and biochemical laboratory parameters are significantly associated with histological disease activity in inflammatory bowel disease. Nevertheless, no single laboratory marker is sufficient to reliably predict histological activity on its own. A combined evaluation of laboratory parameters may contribute to the non-invasive monitoring of histological activity. These findings may help reduce patient burden and support earlier optimization of treatment strategies within the framework of the treat-to-target approach in clinical practice.