Funding for this research was provided by:
H2020 European Research Council (643708)
Received: 18 November 2019
Accepted: 29 January 2020
First Online: 12 March 2020
Ethics approval and consent to participate
: This study was conducted according to the guidelines laid down in the Declaration of Helsinki and all procedures involving human subjects were approved by the ethics committees in all countries (in Belgium, by the Medical Ethics Committee of the Ghent University Hospital; in Bulgaria, by the Ethics Committee of the Medical University of Varna; in Finland, by the hospital district of Southwest Finland ethical committee; in Greece, by the Bioethics Committee of Harokopio University; in Hungary, by the National Committee for Scientific Research in Medicine; in Spain, by the Clinical Research Ethics Committee). All subjects (adults and parents of children) signed an informed consent form before enrolling in the study, while children assented orally before being measured.
: Not applicable.
: OA is a member of the Editorial Board of BMC Endocrine Disorders. The authors have no competing interests to declare.