1. Department of Internal Medicine 1, Division of Nephrology; University of Würzburg; Würzburg Germany
2. Clinical Institute of Medical and Chemical Laboratory Diagnostics; Medical University of Graz; Graz Austria
3. Department of Internal Medicine, Division of Endocrinology and Nuclear Medicine; Medical University of Graz; Graz Austria
4. Department of Epidemiology and Biostatistics, VU University Medical Center; EMGO Institute for Health and Care Research; Amsterdam The Netherlands
5. Department of Nephrology; University of Heidelberg; Heidelberg Germany
6. Synlab Center of Laboratory Diagnostics; Heidelberg Germany
7. Mannheim Institute of Public Health; Ruperto Carola University Heidelberg, Medical Faculty Mannheim; Mannheim Germany