Estimation of differential renal function in unilateral hydronephrotic kidneys with asymmetrical renal area ratio: Comparison of classical and unit area corrected methods

Introduction: Differential renal function calculation plays an important role in surgical decisions in hydronephrotic kidneys, which may show false-positive or false-negative results owing to the asymmetrical renal area in hydronephrotic kidneys. The disparity between the visual and quantitative estimations of renal function can complicate decision making for renal interventions at the optimal time. This study was designed to evaluate whether correcting the differential renal function (DRF) estimation according to kidney unit area can be a more valuable predictor of the functional status of a hydronephrotic kidney than the classical geometric mean method.Methods: Tc-۹۹m Dimercaptosuccinic acid ([۹۹mTc]Tc-DMSA) scans and ultrasonography finding of ۵۲۴ patients with unilateral hydronephrosis due to urinary tract obstruction were reviewed. Differential renal function estimated by both classical geometric mean and unit area corrected method were compared. The correlations of the differential renal function values with the visual classification and the hydronephrosis grades were assessed.Results: The mean Differential renal function by the classical geometric mean and the unit area corrected method of the hydronephrotic kidneys was ۴۱.۲%±۱۲.۳ and ۳۶.۶%±۹.۹ respectively, with mean difference of ۴.۶±۷.۷% (p<۰.۰۰۱). With increasing hydronephrosis grade, differential renal function decreased significantly by the unit area corrected method (p<۰.۰۰۱).Conclusion: Our results suggest that differential renal function estimation by the unit area corrected method is more reliable than by the classical geometric mean method in unilateral enlarged hydronephrotic kidney to avoid misinterpretation due to over-estimation of renal function.

کلیدواژه ها:

[۹۹mTc]Tc-DMSA ، Hydronephrosis ، Differential renal function