Sonographically determined kidney measurements are better able to predict histological changes and a low CKD-EPI eGFR when weighted towards cortical echogenicity

Abstract

Background: The renal length and cortical echogenicity have shown correlation to the renal function and histological changes in CKD patients. The aim of this study was to assess the accuracy of crude and composite ultrasound parameters based on kidney measurements and cortical echogenicity to detect renal dysfunction and histological changes. Methods: Kidney sonography and biopsy were performed in 112 patients. Histological changes were graded in 0, < 25%, ≥25%, ≤50 and > 50% of the sample. Cortical echogenicity was graded relative to liver or spleen parenchyma: less than, equal to and higher than the liver/spleen. Kidney length, the kidney length/body height ratio (KL/H) and cortical thickness were obtained. Each parameter was multiplied by a cortical echogenicity-weighting arbitrary factor: 1.17, 1 or 0.69 for cortex less than, equal to or higher than the liver, respectively. The GFR was estimated using the CKD-EPI formula. The accuracy of crude and composite parameters to identify patients with a high creatinine, a low GFR and histological changes were evaluated. Results: The discriminative power of kidney length and cortical thickness for renal dysfunction and histological changes was improved after weighting for cortical echogenicity. However, the best discriminative was the kidney length to height ratio weighted towards renal echogenicity (w-KL/H). Conclusion: w-KL/H exceeded the other parameters as a marker of renal impairment and histological changes in CKD. Calculation of the w-KL/H index may be of help as a non-invasive tool to identify patients with significant renal disease and might be useful to guide therapeutic decisions.