Relationship Between Serum Uric Acid Levels and Intrarenal Hemodynamic Parameters

Abstract

<b><i>Background/Aims: </i></b>Hyperuricemia has been reported to affect renal hemodynamics in rat models. We evaluate the relationship between serum uric acid and intrarenal hemodynamic parameters in humans, utilizing the plasma clearance of para-aminohippurate (C<sub>PAH</sub> ) and inulin (C<sub>in</sub>). <b><i>Methods: </i></b>Renal and glomerular hemodynamics were assessed by simultaneous measurement of C<sub>PAH</sub> and C<sub>in</sub> in 58 subjects. Of these, 19 subjects were planned to provide a kidney for transplantation; 26 had diabetes without proteinuria; and 13 had mild proteinuria. Renal and glomerular hemodynamics were calculated using Gomez`s formulae. <b><i>Results: </i></b>C<sub>in</sub> was more than 60 ml/min/1.73m<sup>2</sup> in all subjects. Serum uric acid levels correlated significantly with vascular resistance at the afferent arteriole (R<sub>a</sub>) (r = 0.354, p = 0.006) but not with that of the efferent arteriole (R<sub>e</sub>). Serum uric acid levels (β = 0.581, p = <0.001) were significantly and independently associated with R<sub>a</sub> after adjustment for several confounders (R<sup>2</sup> = 0.518, p = <0.001). <b><i>Conclusions: </i></b>These findings suggest, for the first time in humans, that higher serum uric acid levels are associated significantly with R<sub>a</sub> in subjects with C<sub>in</sub> > 60 ml/min/1.73m<sup>2</sup>. The increase in R<sub>a</sub> in subjects with higher uric acid levels may be related to dysfunction of glomerular perfusion.