Visit 7 (study closure, month 30): The current medication of the patient will be recorded (with especial emphasis on the following concomitant medications: ACE inhibitors, AngII blockers, statins, erythropoietin, beta-blockers). Questions will be asked about newly developed diseases with special attention to the occurrence of diabetes mellitus, coronary heart disease, stroke (including transitory ischaemic attacks [TIA] and prolonged reversible ischaemic neurological deficits [PRIND]) and peripheral arterial occlusive disease. The blood pressure, pulse rate and body mass index will be recorded. The study medication will be counted. Questions will be asked about side-effects. The patient will be asked about current symptoms. Laboratory values will be recorded in the course of the routine monitoring of the patients (abbreviated and extensive routine laboratory: hemoglobin, leukocyte count, platelet count, calcium, calcium x phosphate product, urea, serum creatinine, total protein, parathyroid hormone, cholesterol, triglycerides and ferritin).