1. Dutch Growth Foundation (D.A.M.F., A.C.S.H.-K.), 3016 AH Rotterdam, The Netherlands
2. Department of Clinical Chemistry (A.v.T.), Erasmus Medical Center Rotterdam, 3000 CA Rotterdam, The Netherlands
3. Netherlands Institute for Health Sciences (H.J.D.), Erasmus Medical Center Rotterdam, 3000 CA Rotterdam, The Netherlands
4. Department of Pediatric Endocrinology (A.C.S.H.-K.), Erasmus Medical Center Rotterdam, 3000 CB Rotterdam, The Netherlands