[1] Med Univ Graz, Div Endocrinol & Metab, Dept Internal Med, A-8036 Graz, Austria
[2] Med Univ Graz, Clin Inst Med & Chem Lab Diagnost, A-8036 Graz, Austria
[3] Univ Wurzburg, Dept Med, Div Nephrol, Wurzburg, Germany
[4] Univ Heidelberg, Dept Nephrol, Heidelberg, Germany
[5] Univ Ulm, Div Endocrinol Diabet & Metab, Grad Sch Mol Diabetol & Endocrinol, Ulm, Germany
[6] Synlab Ctr Lab Diagnost, Heidelberg, Germany
[7] Ruperto Carola Univ Heidelberg, Inst Publ Hlth, Med Fac Mannheim, Mannheim, Germany
[8] Vrije Univ Amsterdam Med Ctr, Dept Epidemiol & Biostat, Amsterdam, Netherlands
[9] Vrije Univ Amsterdam Med Ctr, EMGO Inst Hlth & Care Res, Amsterdam, Netherlands