Plasma uric acid effects on glomerular haemodynamic profile of patients with uncomplicated Type 1 diabetes mellitus

Aims Increased plasma uric acid (PUA) levels are associated with impaired renal function in patients with Type 1 diabetes, but the mechanisms are not well understood. Our aim was to evaluate whether higher PUA levels are associated with increased afferent arteriolar resistance in patients with Type 1 diabetes vs. healthy controls, thereby influencing renal function. Methods PUA, GFR (inulin) and effective renal plasma flow (ERPF; para-aminohippurate) were measured in 70 otherwise healthy patients with Type 1 diabetes and 60 healthy controls. Gomez's equations were used to estimate afferent (RA ) and efferent (RE ) arteriolar resistances, glomerular hydrostatic pressure (PGLO ) and filtration pressure (ΔPF ). The relationships between PUA and glomerular haemodynamic parameters were evaluated by univariable linear regression correlation coefficients. Results In patients with Type 1 diabetes, higher PUA correlated with lower PGLO (P = 0.002) and ΔPF (P = 0.0007), with higher RA (P = 0.001), but not with RE (P = 0.55). These associations were accompanied by correlations between higher PUA with lower GFR (P = 0.0007), ERPF (P = 0.008), RBF (P = 0.047) and higher RVR (P = 0.021). There were no significant correlations between PUA and renal haemodynamic parameters in the healthy controls. Conclusions The association between higher PUA with lower GFR and lower ERPF in patients with Type 1 diabetes is driven by alterations in the estimated RA . PUA-mediated RA may be caused by increased tone or thickening of the afferent renal arteriole, which might potentiate renal injury by causing ischaemia to the renal microcirculation.