Abstract: TH-PO505

Clinical Advantage of Renal Arterial Doppler Ultrasonography for the Assessment of Tubulo-Interstitial Nephropathy

Session Information

Category: Chronic Kidney Disease (Non-Dialysis)

  • 305 CKD: Clinical Trials and Tubulointerstitial Disorders

Authors

  • Hatano, Minoru, Saitama Medical Center, Saitama Medical University, Kawagoe, Japan
  • Kanozawa, Koichi, Saitama Medical Center, Saitama Medical University, Kawagoe, Japan
  • Hasegawa, Hajime, School of Medicine, Saitama Medical University, Kawagoe, Saitama, Japan
  • Takayanagi, Kaori, Saitama Medical Center, Saitama Medical University, Kawagoe, Japan
  • Hara, Hiroaki, Saitama Medical Center, Saitama Medical University, Kawagoe, Japan
  • Terao, Masaaki, Saitama Medical Center, Saitama Medical University, Kawagoe, Japan
  • Kawai, Yuichiro, Saitama Medical Center, Saitama Medical University, Kawagoe, Japan
  • Sato, Saeko, Saitama Medical Center, Saitama Medical University, Kawagoe, Japan
  • Iwashita, Takatsugu, Saitama Medical Center, Saitama Medical University, Kawagoe, Japan
  • Shimizu, Taisuke, Saitama Medical Center, Saitama Medical University, Kawagoe, Japan
  • Ogawa, Tomonari, Saitama Medical Center,Saitama Medical University, Kawagoe, Saitama, Japan
Background

At present, potential clinical parameters for the assessment of tubulo-interstitial nephropathy (TIN) are poorly available. Here, we focused on the resistive index (RI) measured by renal arterial doppler ultrasonography (RAUS), and studied its efficacy for the assessment of TIN by comparative analysis with the conventional TIN parameter, urine N-acetylglusaminidase-to-creatinine ratio (NAG index) in patients with clinically suspected TIN.

Methods

Patients who have received RAUS under the clinical suspicion of renal artery disorders were retrospectively analyzed (n=33). Clinical diagnosis was renal artery stenosis, (n=13), diabetic nephropathy (n=4) and the others (n=16). We focused on RI measured at two different points independently, with the main trunk of the renal artery (RA) and intra-renal branch of the renal artery (IRA) corresponding to the inter-lobular artery.

Results

An analysis stratified by the median NAG index value for the estimation of TIN revealed a significant difference in the estimated glomerular filtration rate (eGFR), urine protein-to-creatinine ratio (uPCR) and RA/IRA-RI, although the correlation was not significant between the NAG index and the RI. Next, we focused the cases showing NAG index less than 20 U/mgCr because higher NAG index indicates advanced renal damage and the assessment of TIN is not required in those patients. When the patients showing higher NAG index are excluded, IRA-RI showed a significant correlation with NAG index (R=0.59, p<0.01), but RA-RI did not. A multivariate analysis for the NAG index as a response variable revealed that IRA-RI was a significant predictor variable (β=0.59,P=0.02), but RA-RI did not. A ROC analysis showed that the cut-off value of IRA-RI was 0.645 (AUC 0.80, sensitivity 72%, specificity 82%).

Conclusion

Resistive index by RA-US would be a useful clinical parameter for the assessment of TIN. For this purpose, RI should be measured at the intra-renal artery, not the main trunk of renal artery. In addition, threshold of NAG index value indicating the presence of TIN might be lower than the value corresponding the renal artery stenosis (0.8 U/mgCr).