Augmented Association Between Blood Pressure and Proteinuria in Hyperuricemic Patients With Nonnephrotic Chronic Kidney Disease

BACKGROUND Hyperuricemia (HU) may enhance susceptibility to hypertensive renal damage via disrupted autoregulation of glomerular hemodynamics. The effect of HU on the association between blood pressure (BP) and proteinuria remains unknown in patients with chronic kidney disease (CKD). METHODS In total, 109 patients with nonnephrotic CKD (55 men and 54 females) who underwent renal biopsy were recruited. Arteriolar hyalinosis was semiquantitatively assessed via arteriole grading. Correlation between BP and urine protein (UP) level was examined based on the presence of HU, which was defined as the use of urate-lowering drugs or serum uric acid levels of >= 7 and >= 5 mg/dl in males and females, respectively, which were associated with increased risks of hyalinosis in our previous study. RESULTS Median age, BP, estimated glomerular filtration rate, and UP level were 38 years, 124/74 mm Hg, 82 ml/min/1.73 m(2), and 0.8 g/gCr, respectively. In patients with HU (n = 59), log-transformed systolic BP (SBP) was significantly correlated with log-transformed UP level (r = 0.49, P < 0.0001); this was not observed in patients without HU (n = 50). Multiple regression analysis (R-2 = 0.21, P = 0.0001) revealed that the interaction between HU and log-transformed SBP with respect to proteinuria was significantly correlated with log-transformed UP level (beta = 7.0, P = 0.03), independent of age, sex, and potential confounding factors; however, this statistical significance was completely eliminated after adjustment for the arteriolar hyalinosis index. CONCLUSIONS HU potentiates susceptibility to hypertensive glomerular damage via disrupted autoregulation in patients with nonnephrotic CKD.