Individual kidney function in atherosclerotic nephropathy is not related to the presence of renal artery stenosis

Background. Atherosclerotic renovascular disease is increasingly recognized as an important cause of renal failure in patients over 60 years of age but the processes leading to renal dysfunction have not been defined. We have examined the relationship between renal artery stenosis and individual renal function in patients with atherosclerotic renal artery stenosis. Methods. In this prospective descriptive study over a 25-month period, we examined the relationship between the presence of renal artery stenosis and single kidney glomerular filtration rate (SKGFR). SKGFR was measured using a novel method of synchronous (51)Chromium ethylenediamine tetraacetic acid glomerular filtration rate ((51)CrEDTA-GFR) and (99m)Technetium dimercaptosuccinic acid ((99m)TcDMSA) scintigraphy. We studied 79 patients with a mean age of 68.9 years (25.2-88.2), 44 males and 35 females. The mean age of the males was 70 years (60-80) and females 67 years (25.2-88.2). Results, We found that the precision of the SKGFR was 2 ml/min. For paired kidneys we found: (i) no significant difference between kidneys with stenosis (17.3 ml/min) compared to those without stenosis (13.6 ml/min) (P=0.22); (ii) kidneys with occluded renal arteries had significantly less function (2.6 ml/min) than those without occlusion (24.5 ml/min) (P<0.05). When degree of renal arteries stenosis was correlated with SKGFR there was a reduction with an increasing degree of stenosis (< 30% 27 ml/min, 30-60% 17.7 ml/min, >60% stenosis 15 ml/min, P=0.016). Conclusions. These data demonstrate that SKGFR provides a reproducible measure of individual kidney function. There was a similar impairment of function in paired kidneys with and without renal artery stenosis, but occlusion was associated with significant reduction in function compared to the contralateral kidney. This suggests that there is a process causing renal dysfunction in patients with atherosclerotic disease independent of renal artery narrowing.