Sonographic Measurement of Renal Sinus Fat to Renal Cortical Thickness Ratio Is a Better Predictor of Chronic Kidney Disease Than Cortical Thickness Alone

Objective: The aim was to determine if the renal sinus fat-to-cortical thickness ratio was a better predictor of chronic kidney disease (CKD) than cortical thickness alone. Materials and Methods: A total of 199 patients were included in the study. Renal fat, parenchyma, and cortical thicknesses were evaluated by sonography retrospectively. Same day serum glomerular filtration rate (GFR) values were obtained and correlated. Results: The study patients had an average fat-to-cortical thickness ratio <0.4 and had a 63% probability of developing renal failure. The probability increased almost linearly from 65% to 85% for patients with a ratio between 0.4 and 0.5, and then plateaued at 85% probability for a ratio >0.5. Additionally, the average fat-to-cortical thickness ratio was statistically significant (P-value = .02) in predicting progression to renal failure, compared to a cortical thickness alone (P-value = .12 and P-value = .39 for the left and right kidney, respectively). However, when evaluating individual kidneys for the average fat-to-cortical thickness ratio, only the left kidney showed a statistical significance (P-value = .02 and P-value = .08 on the left and right, respectively). Conclusion: The renal sinus fat-to-cortical thickness ratio has a significant negative correlation to GFR, specifically for the left kidney. The probability of developing renal failure increases with higher ratios. The renal sinus fat-tocortical thickness ratio may also be better than cortical thickness alone in predicting progression toward CKD and it acts as an internal control for differences in body size.