1. Division of Biomedical Genetics, Department of Metabolic and Endocrine Diseases, University Medical Center Utrecht, P.O. Box 85090, 3508 AB Utrecht, The Netherlands
2. Netherlands Metabolomics Centre, location Utrecht, P.O. Box 85090, 3508 AB Utrecht, The Netherlands
3. Division Laboratories and Pharmacy, Department of Endocrinology, University Medical Center Utrecht, P.O. Box 85090, 3508 AB Utrecht, The Netherlands
4. Department of Experimental Medical Sciences, Lund University, BMC, C 12, S-221 84 Lund, Sweden
5. Division of Medical Biology, Department of Pathology and Laboratory Medicine, University of Groningen, Hanzeplein 1, 9700 RB, Groningen, The Netherlands
6. Department of Clinical Sciences, Lund University, BMC, C 12, S-221 84 Lund, Sweden