RENAL EXTRACTION OF ATRIAL-NATRIURETIC-PEPTIDE IN UNILATERAL RENAL-ARTERY STENOSIS

1. Elevated peripheral atrial natriuretic peptide (ANP) levels were ob served in 12 patients with unilateral renal artery stenosis (U-RAS). 2 . Renal extraction of ANP was higher across the affected than the unaf fected kidney in U-RAS, provided the glomerular filtration rate in the affected kidney was not severely reduced (>12 mL/min). As ANP is a hi gh clearance compound, reduced flow on the affected side may result in increased renal extraction of ANP. 3. When glomerular filtration rate (GFR) in the affected kidney was severely reduced (<12 mL/min), renal extraction of ANP was also reduced, possibly contributing to increase d circulating ANP levels in this subgroup. 4. Overall, renal extractio n of ANP was inversely correlated to peripheral ANP levels in patients with U-RAS. This might be explained by progressive sodium retention a s GFR falls leading to volume expansion and increased ANP secretion.