Multimodal biomarker approach using urinary prostaglandin E2, kidney injury molecule-1 and resistive index for assessing kidney adaptation in transplant recipients

BACKGROUND: Kidney transplantation is the standard treatment for end-stage renal disease (ESRD). Traditional monitoring with serum creatinine and renal biopsy is limited by delayed detection and invasiveness. Urinary biomarkers including prostaglandin E2 (PGE2) and kidney injury molecule-1 (KIM-1), together with doppler resistive index (RI) may detect early allograft adaptation and subclinical injury. This study aims to evaluate the potential of PGE2, KIM-1 and RI in reflecting post-transplant kidney adaptation. METHODS: We conducted a prospective study of 59 adult living-donor kidney transplant recipients in 2023-2024. Urine and blood were collected pre-transplant and serially post-transplant within 3 months. PGE2 was measured at baseline, day 2, and 1 month, while KIM-1 was analyzed at 1 week. Primary outcome was functional delayed graft function (fDGF). Associations with glomerular filtration rate and resistive index were analyzed using correlation and multivariate regression. RESULTS: Urinary PGE2 on postoperative day 2 was significantly higher in patients with immediate graft function (IGF) and showed the best diagnostic value for fDGF (AUC 0.655; sensitivity 82%; specificity 52%). Urinary KIM-1 was not significantly different between groups and limited predictive value (AUC 0.647). RI at both segmental and arcuate arteries during the first postoperative week was significantly higher in recipients with fDGF (p = 0.045 and p = 0.028, respectively). Day-2 PGE2 correlated with 1st month RI whereas preoperative PGE2 correlated with 1st month postoperative RI at segmental but not arcuate arteries. Multivariate regression reveals KIM-1 and preoperative biomarkers were not predictive while 1-month PGE2 independently predicted 3-month eGFR. CONCLUSIONS: Elevated urinary PGE2 may reflect adaptive hyperfiltration and showed modest predictive value for early graft function. The resistive index was associated with fDGF, while KIM-1 showed inconsistent associations. These findings suggest potential complementary roles of PGE2 and resistive index in the early assessment of kidney transplant adaptation.