Diabetic nephropathy: evaluation with renal duplex Doppler US.

Abstract

To compare Doppler ultrasonography (US) with conventional clinical and laboratory tests in evaluation of diabetic renal disease. Ninety-eight patients with diabetes mellitus underwent renal Doppler (resistive index [RI] measurement) US examination. US data were compared with clinical variables and follow-up data. Thirty-four diabetic patients without nephropathy had a mean RI of 0.62 +/- 0.09, which was not significantly different from the mean RI of 0.64 +/- 0.09 in 23 patients with early diabetic nephropathy. Patients with established nephropathy had a mean RI of 0.83 +/- 0.11, which was significantly (P < .001) higher than in the other two groups. Renal RI correlated highly with serum creatinine concentration (r = .64) and creatinine clearance rate (r = .80). An elevated RI (> or = 0.70) was associated with impaired renal function, increased proteinuria at 24 hours, and poor outcome. Absent diastole (RI = 1.0), observed in 7% of patients, was an ominous sign: Five of seven patients underwent dialysis or transplantation shortly after US. RI is typically elevated in established nephropathy but is often normal in the early clinical stages of disease. Renal Doppler US provides an accurate indication of renal function in diabetic nephropathy but does not offer a great advantage over conventional tests.