Sonographic measurement of renal size in patients undergoing chronic hemodialysis: Correlation with residual renal function

Previous studies have reported that renal size may change when the function is compromised. However, it is not known whether sonographically measured renal size reflects the residual renal function (RRF) in patients undergoing chronic hemodialysis. A total of 140 patients undergoing chronic hemodialysis (≥3 months) were investigated in the present study. The patients were divided into two groups according to the daily urine volume: Individuals with RRF (RRF+ group; ≥200 ml; n=65) and without RRF (RRF- group; <200 ml; n=75). Renal sizes were measured using sonography and renal volumes were calculated with the ellipsoid formula. Univariable and multivariable stepwise forward logistic regression analyses were performed to examine the correlation between the presence of RRF and various variables. The results indicated that there were statistically significant differences (P<0.001) between the RRF+ and RRF- groups with regard to renal length, width, thickness and volume of the left (length, 7.9±1.2 vs. 6.8±1.2 cm; volume, 60.0±26.7 vs. 40.2±18.1 ml, respectively) and right (length, 7.6±1.2 vs. 6.7±1.2 cm; volume, 50.2±26.5 vs. 33.9±15.3 ml, respectively) sides of the kidney. Multivariable stepwise forward logistic regression analyses showed that the mean renal length or volume and hemodialysis duration were independent predictors of the presence of RRF. Therefore, renal size assessment by ultrasonography may be useful for RRF evaluation in patients undergoing chronic hemodialysis.