DPP4 and chronic kidney disease: Experimental studies have shown that urinary dipeptidyl peptidase 4 (uDPP4), unlike serum DPP4 (sDPP4) activity, correlates with proteinuria, serum creatinine, and left ventricular (LV) hypertrophy in chronic kidney disease (CKD) models, suggesting a potential role for uDPP4 in CKD progression.