Functional characteristics of the separate kidneys in hypertensive man

1. 1. Functional studies of the separate kidneys were undertaken in 165 hypertensive patients who had previously undergone excretory urography. Of these, 150 had isotope renography and 147 had renal arteriography. Complications consisted of acute or recurrent pyelonephritis in 4 patients; all responded promptly to appropriate chemotherapy. 2. 2. In 17 hypertensive patients with dominantly unilateral atrophie pyelonephritis, mean values revealed markedly diminished urine volume (54%), clearances of inulin and paraaminohippuric acid (PAH) (65 and 62%), and reabsorption of filtered sodium (1.5%) and water (1.6%) for the diseased kidney. Concentrations of sodium, PAH, and inulin and osmolality of the urine from the diseased side were usually slightly to moderately diminished. In two patients data on urine volume and sodium concentration met criteria for a positive Howard test. 3. 3. Patients with apparent essential hypertension had only minor differences between the kidneys in all parameters studied. The range of differences in those with essential hypertension and aberrant arteries was somewhat greater; however, mean differences were minimal except for greater clearances of inulin and PAH which correlated well with greater renal mass. 4. 4. Of 102 patients with stenosing lesions of the renal arteries, 53 had unilateral and 49 had bilateral obstruction. In patients with unilateral severe renal artery stenosis urine volume and sodium concentration were diminished along with usually diminished clearances of inulin and PAH on the involved side (mean values − 79, − 53, − 47 and − 47%, respectively). Urine osmolality was usually increased as were concentrations of inulin and PAH, the latter two usually by more than 100 per cent. The percentage reabsorption of filtered sodium and water was markedly increased on the involved side (mean values 3.1 and 2.6%, respectively). Patients with unilateral severe renal artery stenosis and aberrant renal arteries differed only in that the mean value for sodium concentration in the urine was only slightly diminished on the involved side (6%). Patients with unilateral renal artery stenosis and partial renal infarction usually could not hyperconcentrate urine on the involved side. Urine volume, sodium concentrations, and osmolality were diminished; however, inulin and PAH concentrations were slightly but consistently increased. When stenosis was severe on one side and mild on the other, functional characteristics were similar to those observed with unilateral stenosis, except for more variable sodium concentrations and osmolality. When stenosis was bilateral and equally severe, significant differences in functional characteristics were seldom observed. Patients with mild or moderate stenosis (less than 50% narrowing of the renal artery) seldom had more than slight differences in functional characteristics. 5. 5. With arteriographically demonstrated renal artery stenosis, (a) increased reabsorption of filtered sodium and water by 1 per cent or more on the involved side, a positive Howard test, and increased osmolality characterized functionally significant lesions and were not seen in essential hypertension; (b) differences in inulin and PAH concentrations largely reflected differences in water reabsorption; and (c) when sodium concentrations were greater on the involved side (negative Howard test), a high incidence of either a branch artery lesion, multiple arteries to the involved kidney, bilateral main artery stenosis, or partial renal infarction was observed.