Are endourological procedures for nephrolithiasis treatment associated with renal injury? A review of potential mechanisms and novel diagnostic indexes

Abstract

Nephrolithiasis is one of the most common urological conditions with a huge socio-economic impact. About 50% of recurrent stone-formers have just one lifetime recurrence and >10% of patients present with a high recurrent disease requiring subsequent and sometimes multiple surgical interventions. The advent of new technology has made endourological procedures the pinnacle of stone treatment, including procedures like percutaneous nephrolithotomy (PCNL), retrograde intrarenal surgery and miniaturized PCNL procedures. Researchers have primarily focused on comparisons with respect to stone-free rates, procedure parameters and post-operative complications. However, the effect of these three procedures on renal function or indexes of renal injury has not been sufficiently examined. This was only reported in a few studies as a secondary objective with the use of common and not the appropriate and detailed renal parameters. This review presents current literature regarding the use of novel and highly predictive biomarkers for diagnosing acute kidney injury, discusses potential mechanisms through which endourological procedures for renal stone treatment may affect renal function and proposes areas with open questions where future research efforts in the field should focus.

Keywords: KIM-1; acute kidney injury; endourology; nephrolithiasis; renal function.

FIGURE 1

Common endourological procedures for the treatment of urinary calculi. (A) ESWL. A correlation between ESWL and AKI has been suggested but more evidence is needed [7]. (B) URS. A semi-rigid ureteroscope is used to treat only ureteral calculi. There is evidence that URS may cause AKI [3] but further research is needed. (C) PCNL. The kidney is punctured and the track is dilated in order to place a sheath for nephroscope insertion and stone fragment removal. PCNL has been associated with AKI but further research is needed [4, 5]. (D) RIRS. A flexible ureteroscope is advanced to the kidney through the ureter in order to perform laser lithotripsy. During RIRS, increased intrarenal pressures are observed, hypothesizing that AKI can manifest following the obstructive uropathy model [6]. Definitive proof of AKI in humans is still lacking.

FIGURE 2

Sheath sizes for different PCNL types. The different types of PCNL differ in the size of the sheath used to access the kidney. An illustration of the different sizes in each type can be seen for comparison. The most common sizes used are 30 Fr for standard PCNL and 16 Fr for mini-PCNL (ultramini- and micro-PCNL are rare and there is no consensus regarding common practice).