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©The Author(s) 2017. Published by Baishideng Publishing Group Inc. All rights reserved.
Reproducibility of serial creatinine excretion measurements in peritoneal dialysis
Zhi Xu, Glen H Murata, Yijuan Sun, Robert H Glew, Clifford Qualls, Darlene Vigil, Karen S Servilla, Thomas A Golper, Antonios H Tzamaloukas
Zhi Xu, Nephrology Division, Department of Medicine, University of New Mexico School of Medicine, Albuquerque, NM 87131, United States
Glen H Murata, Clifford Qualls, Research Service, Raymond G Murphy Veterans Affairs Medical Center, Albuquerque, NM 87108, United States
Yijuan Sun, Darlene Vigil, Karen S Servilla, Renal Section, Medicine Service, Raymond G Murphy VA Medical Center and Department of Medicine, University of New Mexico School of Medicine, Albuquerque, NM 87108, United States
Robert H Glew, Department of Surgery, University of New Mexico School of Medicine, Albuquerque, NM 87131, United States
Thomas A Golper, Division of Nephrology and Hypertension, Vanderbilt University, Nashville, TN 37212, United States
Antonios H Tzamaloukas, Renal Section and Research Service, Raymond G Murphy VA Medical Center and Department of Medicine, University of New Mexico School of Medicine, Albuquerque, NM 87108, United States
Author contributions: Xu Z composed the largest part of the first draft of this report; Murata GH was responsible for part of the statistical analysis and made critical changes in the report; Sun Y assisted in the data collection and made critical changes in this report; Glew RH made critical changes in the manuscript; Qualls C was responsible for part of the statistical analysis; Vigil D made important changes in this report; Servilla KS assisted in the data collection and made important changes in the manuscript; Golper TA conceived the study and made critical changes in the report; Tzamaloukas AH designed the study, assisted in the collection of data and wrote parts of the report.
Institutional review board statement: This study was reviewed and approved by the Human Research Committee of the Raymond G. Murphy VA Medical Center.
Informed consent statement: Patients were not required to give informed consent to this retrospective study because the study used anonymous clinical data obtained to evaluate adequacy of dialytic treatment. Each patient has agreed to the dialytic treatment and the collection of the data used in the study. The institutional Human Research Committee approved the use of these data for this study without a signed informed consent.
Conflict-of-interest statement: We have no financial relationships to disclose.
Data sharing statement: No additional data are available.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Antonios H Tzamaloukas, MD, MACP, Physician, Renal Section and Research Service, Raymond G Murphy VA Medical Center and Department of Medicine, University of New Mexico School of Medicine, 1501 San Pedro, SE, Albuquerque, NM 87108, United States. antonios.tzamaloukas@va.gov
Telephone: +1-505-2651711-4733 Fax: +1-505-2566441
Received: November 8, 2016
Peer-review started: November 10, 2016
First decision: March 8, 2017
Revised: March 21, 2017
Accepted: May 3, 2017
Article in press: May 5, 2017
Published online: July 6, 2017
AIM
To test whether muscle mass evaluated by creatinine excretion (EXCr) is maintained in patients with end-stage kidney disease (ESKD) treated by peritoneal dialysis (PD), we evaluated repeated measurements of EXCr in a PD population.
METHODS
One hundred and sixty-six PD patients (94 male, 72 female) receiving the same PD dose for the duration of the study (up to approximately 2.5 years) had repeated determinations of total (in urine plus spent dialysate) 24-h EXCr (EXCr T) to assess the adequacy of PD by creatinine clearance. All 166 patients had two EXCr T determinations, 84 of the 166 patients had three EXCr T determinations and 44 of the 166 patients had four EXCr T measurements. EXCr T values were compared using the paired t test in the patients who had two studies and by repeated measures ANOVA in those who were studied three or four times.
RESULTS
In patients who were studied twice, with the first and second EXCr T measurements performed at 9.2 ± 15.2 mo and 17.4 ± 15.8 mo after onset of PD, respectively, EXCr T did not differ between the first and second study. In patients studied three times and whose final assessment occurred 24.7 ± 16.3 mo after initiating PD, EXCr T did not differ between the first and second study, but was significantly lower in the third study compared to the first study. In patients who were studied four times and whose fourth measurement was taken 31.9 ± 16.8 mo after onset of PD, EXCr T did not differ between any of the studies. The average EXCr T value did not change significantly, with the exception of the third study in the patients studied thrice. However, repeated determinations of EXCr T in individuals showed substantial variability, with approximately 50% of the repeated determinations being higher or lower than the first determination by 15% or more.
CONCLUSION
The average value of EXCr T remains relatively constant for up to 2.5 years of follow-up in PD patients who adhere to the same PD schedule. However, repeated individual EXCr T values vary considerably in a large proportion of the patients. Further studies are needed to evaluate the clinical significance of varying EXCr T values and the stability of EXCr T beyond 2.5 years of PD follow-up.
Core tip: Total creatinine excretion (EXCr) in urine and in the used peritoneal dialysis (PD) fluid is correlated with muscle mass and has been shown to predict survival and morbidity of patients on PD. This retrospective study evaluated the long-term constancy of 24-h excretion of creatinine in urine and spent peritoneal dialysate from patients with end-stage kidney disease treated by PD. Over a period of 2.5 years, the average value of total EXCr in the study population did not change significantly. However, in individuals there was a substantial variation of repeated measurements of total EXCr above or below its initial value. Approximately half of those studied repeatedly exhibited total EXCr above or below its initial value. Further studies are needed to evaluate changes, both increase and decrease, of EXCr in PD patients and the constancy of EXCr in patients on PD for more than 2.5 years.
