Diabetic nephropathy. Comparison of conventional and duplex Doppler ultrasonographic findings

The purposes of this study were: to compare conventional and duplex Doppler ultrasonography in the detection of renal changes in diabetes mellitus; to investigate whether a correlation was found with various clinical stages; and to assess whether increased renal vascular resistance in asymptomatic patients correlated with mild renal functional impairment.

In 190 diabetic patients and 85 controls, conventional ultrasonography was used to assess renal length, parenchymal thickness, and cortical echogenicity. Renal vascular resistance was estimated by duplex Doppler measurements of intrarenal arterial resistive indices. According to clinical stage, the patients were classified into 3 groups. Resistive indices were compared between controls and patient groups and correlated with age and renal function.

In asymptomatic diabetic nephropathy, renal length and parenchymal thickness were significantly increased compared to that of controls, reflecting hyperfiltration-induced nephromegaly. Differences between controls and patients with clinically manifest nephropathy were insignificant; only in advanced renal disease were both values significantly decreased. Cortical hyperechogenicity was noted only in very advanced disease. Resistive indices correlated well with renal function, and pathologic values (i.e. > or = 0.70) were observed in 15% in the asymptomatic group and in 87% in the group with advanced nephropathy.

Renal changes in diabetic patients are detectable by conventional ultrasound only in very advanced stages of the disease. Pathologic resistive indices, however, may be detected in the earlier stages. Resistive indices correlate with serum creatinine levels and creatinine clearance rates. However, it remains unclear as to whether a diagnostic or prognostic benefit can be expected as compared to standard laboratory examinations.