Calprest ELISA vs. Liaison® chemiluminescence

Background: Ulcerative colitis (UC) management relies on accurately assessing disease activity. Fecal calprotectin (FC) is a promising non-invasive biomarker, but method-specific differences in measurement can affect interpretation. Objective: To compare the performance of Calprest ELISA and DiaSorin Liaison CLIA in measuring FC concentrations and their correlation with endoscopic findings in UC. Methods: Stool samples from 40 UC patients were analyzed using both methods, with 138 samples collected across three clinical timepoints. Spearman’s correlation, Wilcoxon test, Bland–Altman analysis, and ROC curves were used to evaluate method agreement and diagnostic performance relative to Mayo endoscopic scores. Results: A total of 135 paired results showed strong correlation (ρ = 0.795, p < 0.001) but significant inter-method differences (p = 0.039). Liaison tended to yield higher FC values. ROC analysis established optimal cut-offs for detecting endoscopic remission and active disease: 47.95/69.55 µg/g (Liaison) and 65/125 µg/g (Calprest). Calprest demonstrated slightly better diagnostic accuracy. Conclusions: Both methods are reliable for monitoring UC activity. Calprest offers greater dynamic range, while Liaison excels in automation and speed. Method-specific thresholds should guide clinical interpretation to ensure accurate disease monitoring.