1. Dutch Growth Research Foundation (A.J.L., A.C.S.H.-K.), 3001 KB Rotterdam, The Netherlands
2. Department of Pediatrics (A.J.L., A.C.S.H.-K.), Division of Endocrinology, Sophia Children's Hospital, Erasmus Medical Center, 3015 GJ Rotterdam, The Netherlands
3. Department of Internal Medicine (Y.B.d.R., H.v.T., T.J.V.), 3000 CA Rotterdam, The Netherlands
4. Endocrine Laboratory, and Departments of Clinical Chemistry (Y.B.d.R.), 3000 CA Rotterdam, The Netherlands
5. Biostatistics (M.A.J.d.R.), Erasmus Medical Center, 3000 CA Rotterdam, The Netherlands