Usefulness of Resistive Index and Pulsatility Index in Patient with Diabetic Nephropathy as Early Markers / 대한신장학회잡지

ABSTRACT

BACKGROUND: Diabetic nephropathy has long been known as most common culprit of ESRD. In NIDDM, histopathologically intrarenal hemodynamic changes are nonspecific, frequently with global glomerulosclerosis, interstitial fibrosis, tubular atrophy and severe arterosclerosis. Duplex renal Doppler sonography is useful in the noninvasive assessment of intrarenal hemodynamic change and Doppler indices reflect increased renal vascular resistance. So we compared the values of R.I. and P.I., in NIDDM patients, with several clinical parameters to identify that R.I. and P.I. values can reflect increased renal vascular resistance and predict diabetic nephropathy as early markers. METHODS: Renal Doppler US scan was performed on 40 patients with NIDDM to obtain Doppler signals from arcuate artery or interlobar artery and thereby calculate the R.I. and P.I. From every each individual, clinical and laboratory data including age, sex, morbidity period, BMI, mean blood pressure, total cholesterol, serum creatinine, BUN, HbA1c, 24 hr urine protein and creatinine clearance were analyzed. We analyzed the correlation between values of R.I. and P.I. with clinical parameters by using univariate and multiple linear regression analysis. The patients were classified as three groups on the basis of the amount of 24 hour urine protein and value of serum creatinine Group 1(n=15) was defined as patients with 24 hr urine protein less than 150mg/day and serum creatinine less than 1.5mg/ dL, group 2(n=12) as between 150mg/day and 500mg/ day and serum creatinine less than 1.5mg/dL and group 3(n=13) as more than 500mg/day or serum creatinine above 1.5mg/dL. RESULTS: 1) R.I. values showed correlation with age, morbidity period, mean blood pressure, HbA1c, serum creatinine, BUN, creatinine clearance and 24 hour urine total protein. P.I. values showed correlation with age, morbidity period, mean blood pressure, serum creatinine, BUN, creatinine clearance and 24 hour urine total protein. 2) R.I. and P.I. values were significantly affected by creatinine clearance and age in multiple regression analysis. 3) There were statistically positive correlation between 24 hour urine protein and R.I. and P.I.. But when we divided into three groups based on their amount of 24 hour urine protein. R.I. didn't show statistical correlation but P.I. showed significant correlation in the group of patients with proteinuria over 500mg/day(p<0.05). CONCLUSION: Renal doppler indices reflect increased renal vascular resistance in NIDDM patients and correlate with clinical parameters of diabetic nephropathy. We suggest that the R.I. and P.I. are useful marker for indicating diabetic vascular complication in NIDDM patients. However, further comparative studies should be carried out to elucidate the usefulness of R.I. and P.I. as early markers or advantaging parameters in predicting diabetic nephropathy.