1. Department of Endocrinology (G.R., W.d.R.), Vrije Universiteit Medical Center, 1007 MB Amsterdam, The Netherlands
2. Department of Internal Medicine (F.H.d.J.), Erasmus Medical Center, 3000 DR Rotterdam, The Netherlands
3. Department of Internal Medicine (J.-M.K.), Ghent University Hospital, B-9000 Ghent, Belgium