Aspirin-Induced Depression of Glomerular Filtration Rate in Normal Humans: Role of Sodium Balance

Abstract

Renal clearance of endogenous creatinine, inulin and p-aminohippurate was measured in 10 healthy human volunteers taking aspirin during severe dietary Na restriction (10 meq/day) to clarify the clinical significance and pathophysiology of aspirin-induced changes in renal function. Na restriction alone had no effect on renal clearances but did increase plasma renin activity and urinary prostaglandin E excretion. The addition of aspirin decreased the urinary clearance of prostaglandin E but not plasma renin activity and caused a significant fall in endogenous creatinine (from 92.3 .+-. 4.1 SE ml/min per 1.73 m2 body surface area to 80.8 .+-. 4.4 P = 0.02) and inulin (from 95.3 .+-. 7.0 ml/min per 1.73 m2 to 80.9 .+-. 7.0, P < 0.001). The fall in inulin clearance was related to the salicylate level. The clearance of p-aminohippurate showed only a slight, statistically insignificant decline with aspirin. Aspirin-induced depression of glomerular filtration rate may be independent of total renal plasma flow. Aspirin should be used cautiously, with careful attention to dosage, in Na-restricted patients whose glomerular filtration rate may, in part, be under the homeostatic control of renal prostaglandins.