The usefulness of renal length in the ultrasonographic monitoring of renal size

Renal ultrasonography is useful in the screening of pediatric chronic kidney disease (CKD), and studies on renal length have been used as a simple index. Renal length correlates with age and body height, the standard values of which can be obtained by calculations. In enlarged kidneys such as cystic or single kidney, and in atrophic kidneys, such as hypoplastic/dysplastic kidney or renal scarring, the renal length would help to distinguish the disease. In CKD, kidney size decreases with renal function decline. In cases with congenital anomalies of the kidney and urinary tract or low-birth-weight infants that cause CKD in children, the renal length should be evaluated. However, the standard value of the renal length may differ between countries and races. Therefore, studies are needed to identify more accurate standard values for the Japanese population to evaluate slight differences in renal length in the screening and follow-up for CKD.