The effect of obesity on kidney length in a healthy pediatric population.

Over the past decade, the percentage of children who are obese has rapidly increased. As weight has been shown to correlate strongly with the size of various organs, we have observed that obese children have larger kidneys than their normal-weight counterparts. This study sought to quantify this observation by establishing the normal limits of renal length for this population. We examined 204 healthy patients seen for benign hematuria between January 2000 and May 2008. Both right and left kidney lengths significantly correlated with age, height, weight, body mass index and body surface area in our obese patients (n = 59). Height was also found to be a significant predictor of kidney length, in the obese group, by multiple linear regression analysis and was used to create renal length nomograms for the obese pediatric population (P < 0.01). According to this analysis, obese patients had significantly larger kidneys than those of normal-weight patients (P < 0.01). By defining the normal limits of renal length for this group, unnecessary evaluation for nephromegaly will be avoided.