The R package
The R package to calculate leptin z-score and leptin percentiles is available at https://cran.r-project.org/web/packages/childsds/index.html

Brandt-Heunemann S, Vogel M, Kiess W, Körner A, Blüher M, Meigen C, Stein R, Wenzel E, Landgraf K, von Schnurbein J, Denzer C, Lennerz BS, Elad L, Kornmann M, Pridzun L, Rothenbacher D, Steinacker JM, Janda A, Rutters F, Elders PJM, Neuhäuser-Berthold M, Boeing H, Juul A, Ranke MB, Kratzsch J, Wabitsch M. Reference Values for Serum Leptin Levels in Children, Adolescents, and Adults With Normal Weight, Overweight, and Obesity. J Clin Endocrinol Metab. 2025 https://doi.org/10.1210/clinem/dgaf439