The AUC values of miR‐223 in serum, tissue and feces to diagnose CD were all greater than 0.8, which were similar to those of CRP and FC; the AUC values of tissue and fecal miR‐223 for evaluating CD disease activity were 0.832 and 0.818, respectively, which were more precise than those of serum miR‐223, CRP and FC. The gene discussed is CRP; the disease is Cowden disease.