Influence of ureteral obstruction (hydronephrosis) on renal function in man

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Abstract
Ten cases of pelvic dilatation due to obstruction of urinary flow are presented. They were investigated by means of selective clearances for the separate kidneys. GFR (clearance of inulin), ERPF (clearance of PAH) and maximal tubular excretory capacity (TmPAH) were determined, together with the extraction ratio of PAH (EPAH). In four additional cases the changes in the functional pattern of each kidney were studied after the removal of the existing obstruction to urine outflow. The results indicate that partial obstruction to the urinary flow results in lowered CIn/CPAH ratios and generally elevated CPAH/TmPAH ratios, indicating ‘relative renal hyperemia.’ The TmPAH and EPAH did not seem to be primarily affected by the obstruction. The lowered CIn/PAH ratios seemed to be due to diminished GFR or increased ERPF or both. Upon removal of the obstruction the decreased renal activities rapidly recovered simultaneously with a disappearance of the compensatory hyperfunction of the other kidney. The determination of selective clearances offers a possible method for establishing whether or not calculi or strictures obstruct urinary outflow. Submitted on October 6, 1958