Department of Nephrology, Peking University International Hospital, No.1 Life Park Road, Zhongguancun Life Park, Changping District, Beijing, PR China. Electronic address: zhangdongliang@pkuih.edu.cn. Faculty of Nephrology, Capital Medical University, PR China; Department of Nephrology, Beijing Friendship Hospital of Capital Medical University, PR China. George Warren Brown School, Washington University, USA. Department of Nephrology, Beijing Friendship Hospital of Capital Medical University, PR China. Department of Nephrology, Beijing Rehabilitation Hospital of Capital Medical University, PR China.