1. Department of Nephrology
2. Department of Clinical Chemistry and Laboratory Medicine
3. Department of Rheumatology, Leiden University Medical Centre, Leiden, Netherlands
4. Department of Rheumatology and Clinical Immunology, Medical Centre, Faculty of Medicine, University of Freiburg, Freiburg
5. Department of Rheumatology and Clinical Immunology, Charité–University Medicine Berlin, Berlin, Germany
6. Centre for Rheumatology, Division of Medicine, University College London, London, UK