Does a high peritoneal transport rate reflect a state of chronic inflammation?

It has recently been reported that a high peritoneal transport rate was associated with increased mortality in continuous ambulatory peritoneal dialysis (CAPD) patients. One possible explanation is that a high peritoneal transport rate might be caused by a state of chronic inflammation, which also per se might result in increased mortality. Therefore, in this study we investigated whether high peritoneal transport rate patients are in a state of chronic inflammation.

The study included 39 clinically stable peritoneal dialysis patients (free of peritonitis) who had been on PD for more than 3 months (16.8+/-11.8 months). Seven patients were treated with continuous cycling peritoneal dialysis (CCPD) and the others were on CAPD. A 4-hour standard peritoneal equilibration test (PET) using 2.27% glucose solution was performed in each patient. Dialysate samples at 4 hours and blood samples at 2 hours were measured for interleukin-1beta (IL-1beta), tumor necrosis factor(alpha)(TNFalpha), C-reactive protein (CRP), and hyaluronan as markers of inflammation.

There was no significant correlation between dialysate/plasma (DIP) creatinine (0.82+/-0.15, range 0.51 - 1.15) and blood concentrations of IL-1beta (11.2 ng/L, range <5 - 65.9 ng/L),TNFalpha (12.1 ng/L, range <5 - 85.4 ng/L), CRP (<10 mg/L, range <10 - 76 mg/L), nor with the blood hyaluronan concentration (165 microg/L, range 55 - 955 microg/L). The dialysate concentrations of IL-1beta and TNFalpha were below the detectable level in most of the samples. Although dialysate hyaluronan concentration (334 microg/L, range 89 - 1100 microg/L) was correlated with D/P creatinine (r= 0.36, p< 0.05), there was no correlation between the total amount of hyaluronan in the effluent and D/P creatinine. However, a significant correlation was found between serum hyaluronan concentration and glomerular filtration rate (GFR) (r = -0.49, p< 0.005); GFR also tended to be correlated with serum TNFalpha (r = -0.31, p = 0.058) but not with serum IL-1beta and serum CRP.

Our results suggest that a high peritoneal transport rate is not necessarily related to a state of chronic inflammation in CAPD patients. The high mortality rate observed in high transporters may relate to other issues, such as fluid balance or abnormal nutrition and metabolism, rather than to chronic inflammation.