Purpose: Ultrasonography (US) is an inexpensive, noninvasive and easy imaging procedure to comment on the kidney disease. Data are limited about the relation between estimated glomerular filtration rate (e-GFR) and all 3 renal US parameters, including kidney length, parenchymal thickness and parenchymal echogenicity, in chronic kidney disease (CKD). In this study, we aimed to investigate the association between e-GFR and ultrasonographic CKD score calculated via these ultrasonographic parameters.
Methods: One hundred and twenty patients with stage 1-5 CKD were enrolled in this study. The glomerular filtration rate was estimated by the Chronic Kidney Disease Epidemiology Collaboration equation. US was performed by the same radiologist who was blinded to patients' histories and laboratory results. US parameters including kidney length, parenchymal thickness and parenchymal echogenicity were obtained from both kidneys. All 3 parameters were scored for each kidney, separately. The sum of the average scores of these parameters was used to calculate ultrasonographic CKD score.
Results: The mean age of patients was 63.34 ± 14.19 years. Mean kidney length, parenchymal thickness, ultrasonographic CKD score and median parenchymal echogenicity were found as 96.2 ± 12.3, 10.97 ± 2.59 mm, 6.28 ± 2.52 and 1.0 (0-3.5), respectively. e-GFR was positively correlated with kidney length (r = 0.343, p < 0.001), parenchymal thickness (r = 0.37, p < 0.001) and negatively correlated with CKD score (r = -0.587, p < 0.001) and parenchymal echogenicity (r = -0.683, p < 0.001). Receiver operating characteristic curve analysis for distinction of e-GFR lower than 60 mL/min showed that the ultrasonographic CKD score higher than 4.75 was the best parameter with the sensitivity of 81% and positive predictivity of 92% (AUC, 0.829; 95% CI, 0.74-0.92; p < 0.001).
Conclusion: We found correlation between e-GFR and ultrasonographic CKD score via using all ultrasonographic parameters. Also, our study showed that ultrasonographic CKD score can be useful for distinction of CKD stage 3-5 from stage 1 and 2. We suggested that the ultrasonographic CKD score provided more objective data in the assessment of CKD.
Keywords: Chronic kidney disease; Kidney length; Parenchymal echogenicity; Parenchymal thickness; Ultrasonographic chronic kidney disease score; e-Glomerular filtration rate.