1 Division of Paediatric Endocrinology, Department of Paediatrics, Willem-Alexander Children's Hospital, Leiden University Medical Centre, Leiden, The Netherlands.
2 Division of Paediatric Endocrinology, Department of Paediatrics, Erasmus University Medical Centre, Sophia Children's Hospital, Rotterdam, The Netherlands.
3 Division of Paediatric Endocrinology, Department of Paediatrics, Wilhelmina Children's Hospital, University Medical Centre Utrecht, Utrecht, The Netherlands.
4 Division of Paediatric Endocrinology, Beatrix Children's Hospital, University Medical Centre Groningen, Groningen, The Netherlands.