INCREASE IN URINARY CALCIUM AND OXALATE AFTER FRUCTOSE INFUSION

We have previously shown that an oral glucose load increased both calc iuria and oxaluria while the ingestion of fructose induced a rise in c alciuria and a decrease in oxaluria. This latter effect remains unclea r and might be linked to the reduced intestinal oxalate absorption sub sequent to digestive intolerance in some subjects. Such a hypothesis c ould be enlightened by the study of a parenteral fructose load. Theref ore in 7 healthy subjects, we compared the effects of fructose infusio n (F) (15 min iv infusion at 0.185 mmol/kg BW/min) to a control glucos e infusion (G) on urinary calcium and oxalate. In this study, glycemia and insulinemia increased less after (F) than after (G) (respectively + 21 % vs + 216 %, p < 0.001 and + 230 % vs + 402 %, p < 0.05) and ph osphatemia decreased less after (F) than after (G) (-7 % vs 14%, p < 0 .05). Urinary calcium and oxalate increased only after (F) (respective ly + 64 %, p < 0.01 and + 60 %, p < 0.05). Urinary uric acid, another urolithiasis factor, increased after both (F) and (G) (respectively 45 %; p < 0.01 and + 42 %; p < 0.01) but uricemia increased only after (F) (+ 25 %: p < 0.01). Our results suggest an additional reason to a void the use of fructose in parenteral nutrition, particularly in indi viduals with a known history of either calcium oxalate or urate urolit hiasis.