1. Department of Internal Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
2. Division of Internal Medicine and Hypertension, Department of Medical Sciences, University of Turin, Turin, Italy
3. Institute of Clinical Chemistry and Laboratory Medicine, Technische Universität Dresden, Dresden, Germany
4. Medizinische Klinik und Poliklinik IV, Klinikum der Ludwig-Maximilians-Universität München, Munich, Germany