1. Department of Nephrology, The Affiliated Hospital of Qingdao University, Qingdao, China
2. Department of Nephrology, Qingdao Central Hospital, Qingdao, China
3. Reproductive Medicine Center, Qingdao Women and Children's Hospital, Qingdao, China
4. Division of Nephrology, Medizinische Klinik und Poliklinik IV, Klinikum der Universität, Munich, Germany