An observational 3-year follow-up study for postoperative renal function changes assessed by 99 mTc-DTPA scintigraphy and predictive factors after miniaturized percutaneous nephrolithotomy and retrograde intrarenal surgery.

BACKGROUND

This study aims to investigate changes in relative renal function three years after miniaturized percutaneous nephrolithotomy (mini-PCNL) and retrograde intrarenal surgery (RIRS) and to identify significant predictors associated with renal function aggravation.

METHODS

From 2019 to 2023, 355 patients aged 20 and above who underwent mini-PCNL or RIRS for the treatment of renal stones > 10 mm in maximal diameter were prospectively included in this study, with those who had separate renal function serially traced being included. Among them, 93 patients were included in the analysis. Renal function was evaluated using 99 mTc-DTPA before surgery, and at 3 months, 1, 2, and 3 years postoperatively.

RESULTS

A difference in preoperative renal function of > 10% between the contralateral and operative sides was observed in 79 patients (84.9%). Among those in the abnormal renal function group, 42 patients (53.2%) showed stability, 31 (39.2%) showed aggravation, and 6 (7.6%) showed improvement in renal function at postoperative 3 years. Functional changes did not differ significantly between the types of surgery. Significant predictors of renal function aggravation included higher preoperative creatinine levels, preoperative hydronephrosis, and S-ReSC > 3.

CONCLUSION

A key point of this study is that it is important to explain to patients who do not show recovery within 1 to 2 years that there is a 42.1% chance their renal function may deteriorate over time. Clinicians should be particularly attentive to renal function in patients with higher preoperative creatinine levels, preoperative hydronephrosis, and S-ReSC > 3, requiring closer monitoring and management.