WFDC2 and chronic kidney disease: The whole process is simple and fast, and the results demonstrated serum HE4 to be significantly associated with renal fibrosis in CKD patients, and ROC analysis demonstrated that serum HE4 is more suitable as an eligible biomarker for distinguishing renal fibrosis from CKD patients than serum creatinine (AUC-ROC of HE4 vs. creatinine was 0.99 vs. 0.89, respectively).