US-derived Pediatric Kidney Length and Volume Percentiles by Age: A Big Data Approach

Purpose To calculate new pediatric age-specific normative values and percentiles for kidney length and volume through the use of a natural language processing (NLP) model. Materials and Methods In this cross-sectional study, 24664 US reports from 18769 children (birth to 18 years) conducted between January 2012 and December 2022 at a tertiary children's hospital in the northeastern United States were analyzed with an NLP model. Anthropometric data from 12595 children were used to evaluate the impact of sex and body measurements on kidney length and volume through age-adjusted quantile regression models. Age-related percentiles were established after calibration, using the lambda-mu-sigma (LMS) method by age (year), with detailed subcategories for children under 1 year. Volume percentiles by body surface area were also generated using the LMS method. Results A total of 24664 reports from 18769 children were included (median age, 7 years [IQR = 11], 10134 females). Normative value analysis showed that kidney growth was more pronounced in the first year of life (1.8-cm increase in length and 16.9-cm 3 increase in volume). The large sample size resulted in standard errors that were 10–30% less than previous normative values. Quantile regression models showed that body surface area was a better predictor of kidney volume than age (R1 = 0.57 [ P < .001] vs 0.48 [ P < .001]). Conclusion New LMS percentiles for kidney size were established using data from a large pediatric sample.