Value of resistive index in patients with clinical diabetic nephropathy

OBJECTIVE. To determine whether the intrarenal resistive index (RI) can be used as a predictor in patients with advanced clinical diabetic nephropathy. METHODS. Sixty-eight kidneys belonging to 34 patients with type II diabetes mellitus and 100 kidneys of 50 healthy persons (control group) were evaluated with Doppler ultrasonography. RI values were obtained from intraparenchymal arteries, either the arcuate or interlobar arteries. Patients with diabetes were divided into two groups based on serum creatinine concentration: group 1 (n = 21 patients, 42 kidneys) bad a serum creatinine concentration <1.4 mg/dL and group 2 (n = 13 patients, 26 kidneys) bad a serum creatinine concentration >1.4 mg/dL. Regression analysis was used to examine the relations between intrarenal RI and age, serum creatinine concentration, and creatinine clearance rate. RESULTS. The mean RI value (0.69 ± 0.1) in patients with diabetes was significantly different from that of healthy subjects (0.56 ± 023) (P < 0.00001). The RI value of the patients in group 2 (0.79 ± 0.07) was significantly different from that of the patients in group 1 (0.61 ± 0.04, P < 0.00001). Serum creatinine concentration and creatinine clearance rate showed high correlations (r = 0.84 and r = -0.76, respectively) with intrarenal RI values. CONCLUSIONS. Because the intrarenal RI shows a high level of correlation with serum creatinine concentration and creatinine clearance rate, it can be used as a predictor in patients with advanced clinical diabetic nephropathy. Intrarenal RI does not offer any advantage over serum creatinine concentration and creatinine clearance rate in patients with early-stage diabetic nephropathy with normal renal function.