Fn exhibited a slightly higher diagnostic value than Fp in distinguishing CD from HS (Area Under Curve, AUC = 0.841 vs. 0.811) or irritable bowel syndrome (IBS) groups (AUC = 0.767 vs. 0.658), and the further combination of Fn and Fp improved the diagnostic value (HS, AUC = 0.867; IBS, AUC = 0.771). Here, FN1 is linked to irritable bowel syndrome.