1. Department of Endocrinology and Metabolism (L.P.K., H.P.S., A.K., E.F.), Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands
2. Department of Endocrinology and Metabolic Diseases (C.P.C., L.M.H., P.J.V., P.C.N.R., J.A.R.), Leiden University Medical Center, 2300 RC Leiden, The Netherlands
3. Department of Clinical Chemistry, Laboratory of Endocrinology (E.E.), Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands
4. Netherlands Institute for Neuroscience (A.K.), 1105 BA Amsterdam, The Netherlands