Can renal sonography be a reliable diagnostic tool in the assessment of chronic kidney disease?

OBJECTIVES

Kidney size has been found to be correlated with anthropometric features and kidney function. Therefore, we postulate that if the conventionally measured renal sonographic parameters (pole-to-pole length, width, and parenchymal thickness) are taken according to standardized rules and corrected for body height, their association with kidney function could be strengthened, thus helping validate renal sonographic information for a better assessment of chronic kidney disease (CKD) status.

METHODS

This cross-sectional study included 72 stable adult patients with stage 1 to 4 CKD. Sonographic parameters were obtained from both kidneys and averaged, and the measurements obtained were further corrected for patients' body height. The glomerular filtration rate (GFR) was estimated by the Chronic Kidney Disease Epidemiology Collaboration equation.

RESULTS

Parenchymal thickness and renal length showed the highest correlation level with the GFR. This significant correlation, however, was greatly ameliorated by the correction for patients' body height (r = 0.537; P < .001; r = 0.510; P < .001, respectively). Of note, the product of these two parameters corrected for body height showed the best degree of correlation with the GFR (r = 0.560; P < .001), as confirmed by analysis of variance after subdivision of the population into CKD stage groups according to the GFR. Receiver operating characteristic curve analysis for discrimination of a GFR of less than 60 mL/min indentified the combined parameter as the one with the highest area under the curve (0.78; 95% confidence interval, 0.66-0.89), followed renal length corrected for height (area under the curve, 0.77; 95% confidence interval, 0.66-0.88).

CONCLUSIONS

Correction of renal sonographic parameters for body height strengthens the degree of the correlation of renal sonography with the GFR. The improved correlation with the GFR makes renal sonography a reliable tool for a more complete assessment of patients with CKD.