Acute Kidney Injury Following Mini Percutaneous Nephrolithotomy for Renal Stones: predictors and Follow-up Evaluation in Real-life Setting.

Abstract

Purpose: To evaluate the prevalence, predictors, and progression of acute kidney injury (AKI) in patients undergoing mPCNL for nephrolithiasis.

Materials and methods: We retrospectively analyzed data from 569 patients who underwent mPCNL at a single tertiary academic center (01/2016-10/2024). AKI was defined per KDIGO criteria as sCr increase >0.3 mg/dL or ≥1.5× baseline. Stone-free status was no residual stones on CT at 3-month follow-up. Complications were classified using the modified Clavien system. Kidney function was reassessed 30-90 days post-op. Descriptive statistics, logistic regression, and Cox regression were applied.

Results: Median (IQR) age and stone volume were 57 (48-66) years and 2.1 (0.9-4.2) cm³. Median preoperative sCr and operative time were 0.9 (0.7-1.1) mg/dL and 90 (73-120) minutes. Post-mPCNL, 40 patients (7.0%) developed AKI. Complications occurred in 138 (24.2%) patients; 449 (78.9%) were stone-free. AKI patients had higher CCI (1.3 vs. 0.5, p=0.04), pre-op sCr (1.1 vs. 0.8 mg/dL, p<0.01), stone volume (5.7 vs. 2 cm³, p=0.02), and longer operative time (130 vs. 90 min, p=0.01). Complications were more frequent in AKI patients (42.5% vs. 22.8%, p=0.01). At multivariate analysis, operative time (OR 1.1, p=0.03), pre-op sCr (OR 3.8, p=0.001), and early complications (OR 2.5, p=0.02) were independently associated with AKI. AKI persisted in 9 (22.5%) patients, mainly those with complications (88.9% vs. 38.7%, p=0.01). On Cox analysis, lower BMI (HR 0.8, p=0.02) and absence of complications (HR 0.3, p=0.01) predicted faster AKI recovery.

Conclusion: Acute kidney injury remains a clinically significant complication following mPCNL.