As main developers of the European Kidney Function Consortium (EKFC) creatinine-based equation,1 we are puzzled by the results of the EKFC equation in comparison to the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) in young adults presented by Inker et al,2 especially in the 18-25 years age range. Indeed, in our hands, the EKFC equation is particularly better than CKD-EPI in young people, allowing a smooth transition in estimating glomerular filtration rate (GFR) between adolescence and adulthood, a point that is not discussed.