1. Department of Nephrology, Shengli Oilfield Central Hospital, Dongying, Shandong 257000, P.R. China
2. Laboratory Department, Shengli Oilfield Central Hospital, Dongying, Shandong 257000, P.R. China
3. Blood Purification Center, Shengli Oilfield Central Hospital, Dongying, Shandong 257000, P.R. China