A comparison of unilateral pyelonephritis and renal artery stenosis associated with hypertension

A comparison of the findings in fourteen patients with unilateral pyelonephritis and hypertension and fourteen patients with renal artery stenosis and hypertension is made. There was nothing in the preliminary work-up that would routinely separate the two groups, although a history of urinary tract infection was higher in the pyelonephritis group, and an abdominal bruit and hypokalemia were suggestive, when found, of renal artery stenosis. The intravenous pyelogram suggested the correct diagnosis in about three-quarters of instances, but further tests were needed for confirmation. Thus, the renogram pointed to the involved kidney in the majority of instances, but a number of false positives have been observed. Divided renal function studies, with particular emphasis on a comparison of the osmolarity of the urine from the two ureters, was diagnostic of renovascular hypertension, practically without exception, and of unilateral pyelonephritis in three-quarters of instances. A positive aortogram was the final requirement for the diagnosis of renovascular hypertension. Evidence for the operation of the renal pressor mechanism in the renovascular group is cited and corroborated by the good surgical results in 80 per cent of the cases. By contrast, evidence for the operation of a similar mechanism in the group with hypertension associated with unilateral pyelonephritis was lacking, and the comparatively poor results of renal surgery on the hypertensive process was noted. A simple causal relationship between the unilateral pyelonephritis and the hypertensive state cannot be supported although the coincidence of the two disorders probably cannot be relegated to chance alone. At the present time it is difficult to decide which, if any, patients with the latter complex should be subjected to nephrectomy in the hope of improving the hypertension.