1. Fifth Medical Department, Medical Faculty Mannheim, Heidelberg University, D-68167 Mannheim, Germany
2. Department of Medicine I and Clinical Chemistry, Heidelberg University, D-69120 Heidelberg, Germany
3. Department of Dermatology, Heidelberg University, D-69120 Heidelberg, Germany
4. Department of Nephrology, Centre Hospitalier du Nord, 9080 Ettelbruck, Luxembourg
5. Department of Nephrology, Heidelberg University, D-69120 Heidelberg, Germany
6. Klinik f�r Nieren‑, Hochdruck‑ und Autoimmunerkrankungen, Klinikum Stuttgart, D-70174 Stuttgart, Germany