Difficulties in the Evaluation of Hypertension Secondary to Renal Ischemia

Abstract

Reproducible split renal function studies under urea diuresis have made possible the accurate identification of those patients with hypertension secondary to an occlusion of a branch of the main renal artery. Differential renal function studies are presented on 13 patients with segmental renal ischemia due to branch arterial occlusion. These cases all show evidence of excessive sodium and water reabsorption on function study; comparison of the UpAH has been shown to be more diagnostic of renal ischemia than changes in U_Inulin. The major difficulty in evaluating patients with hypertension occurs in those who exhibit no excessive water reabsorption on differential function study. The important observation for diagnosis in these patients is to compare the ratio of urine flow rates to the ratio of renal mass. In those patients with hypertension as a result of unilateral pyelonephritis renal function studies are of limited value.

Evaluation of Differential Renal Function Studies in Segmental Renal Artery Occlusion

“…Another interesting observation, mentioned also by other investigators (Stamey, 1966;Fair, 1970), is the reduced filtration fraction (FF) of the ischaemic kidney as compared to that of the contralateral kidney (Table I) in this patient. This was due to the fact that the GFR was 9 % less and the RPF only 2 % less in the ischaemic kidney than in the contralateral kidney.…”