Do kidney sizes in ultrasonography correlate to glomerular filtration rate in healthy children?

The objective of this study was to determine the correlation between ultrasonographic kidney sizes and glomerular filtration rate (GFR) in healthy children. This was a cross-section study on 116 healthy children. Renal diseases were ruled out by a paediatric nephrologist. Ultra sonography of both kidneys was carried out by an experienced radiologist. The volume was calculated by ellipsoid formula. We defined net volume as kidney volume-sinus fat volume'. The sum of right and left kidney sizes was defined as total sizes. We calculated GFR by means of the Schwartz formula. Correlations between kidney sizes and GFR were studied with Pearson correlation coefficient. The mean age of the children was 8.4+/-3.4. The GFR mean was 108+/-30 (mL/min per 1.73 m2). GFR correlated to total renal volume (r=0.52, P<0.001), total net volume (r=0.53, P<0.001) and total kidney length (r=0.59, P<0.001). Ultrasonographic kidney sizes, especially the kidney length, correlate to GFR in healthy children. Kidney sizes assessment by ultrasonography may play a role in renal function evaluation in children.