Published online Jul 6, 2017. doi: 10.5527/wjn.v6.i4.201
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
Processing time: 233 Days and 16 Hours
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.
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.
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.
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.