Kidney length normative values - new percentiles by age and body surface area in Central European children and adolescents.

Background: Kidney size evaluation is an essential examination in pediatric nephrology. While body length/height is the best predictor of kidney length, age-based and body surface area (BSA)-based normative values may be useful in clinical practice or research. This study aimed to establish ultrasound-based kidney length lambda-mu-sigma (LMS) percentiles by age and BSA in healthy children.

Methods: In 1758 Polish and Lithuanian children (868 boys, 49%) aged 0-19 years, kidney length was measured using ultrasonography. In all participants, anthropometric measurements were taken and kidney function was evaluated based on serum creatinine concentration. Participants with chronic or kidney diseases, abnormal kidney function, or pathologies in sonographic examination were excluded from the analysis.

Results: Kidney length (median kidney length) increased progressively from infancy to the age of 18 years, from 60.1 to 114.2 mm in males, and from 57.3 to 105.2 mm in females. A gradual increase of kidney length (50 percentile) in relation to BSA (from 46.1 mm in infants with a BSA of 0-1.2 m to 118.3 mm in adolescents with a BSA of 2.6-2.8 m) was also observed. LMS percentiles by age (stratified by sex) and BSA were determined and presented as graphs and tables of percentiles and LMS parameters by 1-year age intervals and 0.2 m of BSA, respectively.

Conclusions: We present the first age- and BSA-based kidney length LMS normative values based on the largest pediatric cohort to date, which can be used in both clinical practice and research studies. A higher resolution version of the Graphical abstract is available as Supplementary information.