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Abstract: FR-PO666

Estimating Total Small Solute Clearance in Patients Treated with Continuous Ambulatory Peritoneal Dialysis Without Urine and Dialysate Collection

Session Information

Category: Dialysis

  • 703 Dialysis: Peritoneal Dialysis


  • Fan, Li, The First Affiliated Hospital of Sun Yat-sen University; Key Laboratory of Nephrology, Ministry of Health; Guangdong Provincial Key Laboratory of Nephrology, , Guangzhou, China
  • Steubl, Dominik, Tufts Medical Center, Boston, United States
  • Inker, Lesley, Tufts Medical Center, Boston, Massachusetts, United States
  • Tighiouart, Hocine, Tufts Medical Center, Boston, Massachusetts, United States
  • Karger, Amy B., University of Minnesota, Minneapolis, Minnesota, United States
  • Eckfeldt, John H., University of Minnesota Medical School, Minneapolis, Minnesota, United States
  • Zhang, Hao, The Third Xiangya Hospital of Central South University, Changsha, HUNAN, China
  • Hu, Jing, The third Xiangya hospital of Central South Univercity, Changsha, China
  • Liao, Yunhua, The First Affiliated Hospital of Guangxi Medical University, Nanning, China
  • Shafi, Tariq, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
  • Chen, Wei, The First Affiliated Hospital, Sun Yat-sen University,, Guangzhou, China
  • Yu, Xueqing, Department of Nephrology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
  • Levey, Andrew S., Tufts Medical Center, Boston, Massachusetts, United States

Higher total (kidney plus dialysis) clearance of small solutes is associated with lower mortality in peritoneal dialysis (PD) patients. Measurement of total clearance (mCL) is recommended to monitor and adjust dialysis dose, but is difficult and prone to errors due to the requirement for timed fluid collections. We hypothesized that equations (eCl) could be developed to estimate mCl using serum concentrations of endogenous filtration markers.


Using 2/3 of the participants in the Guangzhou PD Study (N=980), we used linear regression to develop eCl equations. Reference tests were mCl for urea nitrogen (mClUN, ml/min) and average mCl for UN and creatinine (mClUN-cr, ml/min/1.73 m2). Index tests were various eCl equations using UN, creatinine, low-molecular-weight-proteins (LMWP) [beta-trace-protein (BTP), beta-2-microglobulin (B2M), cystatin C], demographic variables and body size. We validated the equations in the remaining 1/3 of the cohort (n=322) and refitted equations in the combined dataset. We analyzed the predictive value of the equations to detect a weekly total standard Kt/V (mClUN per week indexed for total body water) >1.7 using receiver-operating-characteristic curve.


Mean age of the cohort was 50±15 years, 53% were male; mClUN was 6.9±1.8 ml/min, mClUN-cr 7.5±2.8 ml/min/17.3 m2. Creatinine but not UN contributed to eCl (Table). LMWP did not improve accuracy for mClUN (range 87.6-88.6%). BTP and B2M improved accuracy for mClUN-cr (range 81.6-82.0 vs. 79.7%), however, differences were small. The area-under-the-curve for predicting a weekly kt/V >1.7 was similar for all equations (range 0.791-0.802).


Total small solute clearance can be estimated moderately well [TMC1] in CAPD patients from serum concentration of creatinine and demographic variables without urine and dialysate collection. Equations to estimate total clearance need to be evaluated in other cohorts.


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