1. Kantonsspital Graubünden, Zentrallabor, Chur, Switzerland;
2. Labormedizinisches Zentrum Dr. Risch, Liebefeld, Switzerland;
3. Faculty of Medical Sciences, Private University, Triesen, Liechtenstein;
4. University Institute of Clinical Chemistry, University Hospital and University of Bern, Bern, Switzerland;
5. Faculty of Science, Tallinn University of Technology, Tallinn, Estonia;
6. Institute of Laboratory Medicine, Philipps University Marburg, Marburg, Germany;
7. Division of Nephrology, Stadtspital Waid, Zurich, Switzerland;
8. European Center of Pharmaceutical Medicine, University of Basel, Basel, Switzerland;
9. Epidemiology, Biostatistics and Prevention Institute, University of Zurich, Zurich, Switzerland