High-power Ho:YAG lithotripsy increases subclinical renal stress: a prospective randomized KIM-1 study

This study aimed to compare the safety profile of high-power (HPL) and low-power (LPL) Holmium:YAG lasers in retrograde intrarenal surgery (RIRS), using urinary Kidney Injury Molecule-1 (KIM-1) as an early biomarker for acute kidney injury (AKI). Sixty patients with renal stones (1.5-2.5 cm) were prospectively randomized into HPL and LPL groups. Urinary KIM-1 and KIM-1/creatinine ratios were measured preoperatively and at 4 and 24 h postoperatively. Intraoperative parameters, stone-free rates (SFR), complications, and renal function (eGFR, serum creatinine) were also assessed. Intrarenal temperatures were recorded before and after lithotripsy. Operative time, SFR, complication rates, and renal function parameters were similar between groups (p > 0.05). However, KIM-1 levels were significantly higher in the HPL group at 24 h postoperatively (278.8 ± 239.6 pg/mL vs. 170.3 ± 172.9 pg/mL, p = 0.003), and the KIM-1/creatinine ratio was also elevated (5.5 ± 4.5 vs. 3.1 ± 2.0, p = 0.035). No significant differences were observed in postoperative serum creatinine or eGFR. Intraoperative renal temperatures increased slightly in the HPL group, but the difference was not statistically significant. While high-power laser lithotripsy does not adversely affect global renal function, it is associated with elevated levels of renal injury biomarkers, suggesting greater subclinical renal stress.