Urinary kidney injury molecule-1: a novel biomarker to monitor renal function in patients with unilateral ureteral obstruction.

PURPOSE

This study aimed to investigate the clinical significance of urinary kidney injury molecule-1 (KIM-1) to monitor renal function in patients with obstructive unilateral ureteral calculi.

METHODS

Kidneys of 12 male C57BL/6J mice, as well as their urine and plasma specimens, were extracted to detect KIM-1 expressions 24 h after unilateral ureteral obstruction (UUO) construction or sham surgery. Meanwhile, a cohort of 89 patients with unilateral ureteral calculi was retrospectively reviewed. 46 of which received double-J ureteral stent indwelling (group 1) and the remaining 43 were treated conservatively (group 2). Urinary KIM-1 levels in the baseline, 2 h and 1 day after treatments were analyzed.

RESULTS

KIM-1 expressions were dramatically higher in mice underwent UUO surgery when compared with the sham group. Clinical data showed urinary KIM-1 levels decreased as time went by for patients in group 1 (1.787 ± 1.081 ng/mL for baseline, 1.668 ± 1.162 ng/mL for 2 h and 0.935 ± 0.526 ng/mL for 1 day after operation; p = 0.0001). Nevertheless, for those in group 2, a mild increase (1.659 ± 0.997 ng/mL, 1.691 ± 0.872 ng/mL and 1.675 ± 0.911 ng/mL, correspondingly; p = 0.9869) was observed. Additionally, a urinary KIM-1 value of 1.04 ng/mL had a sensitivity of 83.1% and specificity of 62.5% to predict the presence of hydronephrosis (95% CI: 0.641-0.873, AUC: 0.757, p < 0.001).

CONCLUSIONS

Urinary KIM-1 is a sensitive biomarker of post-renal acute kidney injury (AKI) and might predict the presence of hydronephrosis. It can be used as an effective surrogate to monitor renal function.