Supranormal differential renal function in adults with ureteropelvic junction obstruction: Does it really exist?

Area of Science:

• Urology
• Nephrology
• Radiology

Background:

• Ureteropelvic junction obstruction (UPJO) can present with supranormal differential renal function (snDRF).
• Understanding the outcomes of pyeloplasty in these patients is crucial for effective management.
• Identifying predictors of snDRF phenomenon is essential for accurate prognostication.

Purpose of the Study:

• To evaluate pyeloplasty outcomes in adult UPJO patients with snDRF versus normal DRF (nDRF).
• To identify preoperative factors associated with snDRF.
• To assess the reliability of DRF changes in predicting treatment success.

Main Methods:

• Retrospective analysis of pyeloplasty patients with snDRF (DRF ≥55%) and nDRF (DRF 45-55%).
• Correlation of preoperative radiological data (CT/MRI) with snDRF.
• Assessment of pre- and post-operative scintigraphic findings for functional outcomes.

Main Results:

• 31 patients had snDRF (Group 1) and 42 had nDRF (Group 2).
• In Group 1, 22/31 patients experienced DRF reduction post-pyeloplasty (mean DRF decreased from 59% to 48%).
• Increased renal pelvis volume (≥50 mm³) and anteroposterior pelvic diameter (APD ≥37 mm) predicted snDRF and correlated with postoperative DRF decrease.

Conclusions:

• snDRF in UPJO patients is often transient and associated with specific preoperative anatomical findings.
• Increased renal pelvis volume and APD are key predictors of snDRF.
• Absolute DRF values and their changes are unreliable for judging pyeloplasty treatment failure.