Sodium Excretion and Hyperfiltration during Glucose Infusion in Man

Abstract

The relations between renal hemodynamics (Inutest, CPAH) and sodium excretion were studied in 7 nondiabetics in whom a similar expansion was induced (1) with a 3-hour 5% glucose infusion and (2) with a 0.9% saline load. With both infusions the body weight increased, hematocrit fell, and the plasma renin activity was suppressed. During glucose infusion, blood glucose rose from 3.9 mmol/l to a plateau of around 13 mmol/l; glycosuria was absent during the 1st h, then appeared and stabilized during the following 2h. Glucose infusion caused a progressive increase in glomerular filtration rate and in renal blood flow in both absence and presence of glycosuria, without significant changes in sodium excretion despite volume expansion and increase of filtered sodium load. When saline was infused, there was a sustained increase of fractional sodium excretion, and no hemodynamic modifications were observed. We suggest that a primary glucose-induced metabolic stimulation of sodium reabsorption may play a role in the genesis of glucose-induced hyperfiltration.