Renal function in experimental chronic hydronephrosis. III. Glomerular and tubular functions in relation to renal pelvic volume.

Studies of renal function comprising determination of exogenous creatinine clearance, urinary osmolality and TmG were performed on 23 dogs, for each kidney separately, after hydronephrosis with partial ureteric obstruction had been produced by ligation of one ureter over an indwelling catheter. A method for determining the volume of the hydronephrotic renal pelvis was developed and the degree of functional reduction was correlated to the degree of pelvic dilatation. In 11 cases the renal blood flow was determined by direct measurement. Statistically significant reductions of the glomerular and tubular functions were noted on the hydronephrotic side. TmG and the urinary osmolality showed the greatest percentual decreases and the TmG/GFR ratio the smallest. The decrease in this ratio was due to greater deterioration of tubular than of glomerular function. The renal blood flow was reduced on the hydronephrotic side in comparison with the intact side, but seemed relatively less affected than the glomerular and tubular functions. Compensation by the intact kidney resulted in masking of the deterioration on the hydronephrotic side; thus for the whole material the mean GFR and urinary osmolality for the two kidneys together remained essentially unchanged. No statistically significant correlation between the degree of functional reduction and the degree of pelvic dilatation was found. Such a correlation could therefore not be used in the individual case as an indication of the functional capacity of a kidney.