Urinary KIM-1 as a Marker of Renal Tubular Injury Associated with Urethral Obstruction in Non-Azotemic Cats

Cats with urethral obstruction may develop tubular damage before conventional indicators of renal dysfunction become abnormal, making early recognition challenging when relying solely on conventional renal biomarkers. This study evaluated urinary kidney injury molecule-1 (KIM-1) concentrations in non-azotemic cats with urethral obstruction and compared its expression with conventional renal biomarkers. Twenty-four male cats were prospectively enrolled and allocated into a control group (n = 12) and a urethral obstruction group (n = 12), all presenting serum creatinine concentrations within the reference interval. Urinary KIM-1 concentrations were quantified by enzyme-linked immunosorbent assay (ELISA) and normalized to urinary creatinine concentrations. Serum creatinine and blood urea nitrogen (BUN) did not differ significantly between groups. In contrast, urinary KIM-1 concentrations were significantly higher in cats with urethral obstruction compared with healthy controls (p < 0.001). These findings suggest that increased urinary KIM-1 expression may be associated with renal tubular injury in non-azotemic cats with urethral obstruction, even in the absence of alterations in conventional renal biomarkers. Therefore, urinary KIM-1 may represent a useful non-invasive marker of renal tubular injury associated with obstructive urinary disease. Further prospective studies incorporating additional renal biomarkers, histopathological evaluation, and longitudinal follow-up are warranted to better define its clinical applicability.