Evaluation of peritoneal transport and membrane status in peritoneal dialysis: focus on incident fast transporters

BACKGROUND/AIM

The determinants of baseline fast solute transport are still unclear. We prospectively investigated the relationship of peritoneal solute transport with markers of inflammation, angiogenesis, and membrane status, with a focus on fast transporters.

METHODS

Seventy-one incident peritoneal dialysis patients were assessed with baseline and annual peritoneal equilibration tests, using a 3.86% glucose dialysis solution. Residual renal function and markers of inflammation, including systemic and intraperitoneal interleukin-6 (IL-6), effluent cancer antigen 125 (CA-125), and vascular endothelial growth factor (VEGF) appearance rates (ARs), were investigated. The time course of the dialysate-to-plasma ratio of creatinine (D/P creatinine ratio) and its relationship with the biomarkers were investigated by a mixed linear model.

RESULTS

Incident fast/fast average transporters had a similar age, diabetes prevalence, and serum and effluent IL-6 levels, but significantly higher levels of CA-125 and VEGF ARs than the slow/slow average group; the D/P creatinine ratio was not correlated with systemic IL-6, but was correlated with effluent CA-125 AR (r = 0.45, p < 0.0001) and VEGF AR (r = 0.52, p < 0.0001). The D/P creatinine ratio decreased with a U-shaped profile (p = 0.02). Intraperitoneal IL-6 was the significant and positive determinant of the time course of the D/P creatinine ratio (p < 0.0001). Effluent CA-125 decreased with time on peritoneal dialysis (p = 0.013).

CONCLUSIONS

Baseline peritoneal fast transport was not associated with systemic inflammation, but was related to peritoneal locally produced substances able to mediate transitory hyperpermeability. The D/P creatinine ratio changed during the follow-up period with a U-shaped profile. This was associated with effluent IL-6 and partly with VEGF. CA-125 decreased throughout the follow-up period.

Peritoneal dialysis, membranes and beyond

PURPOSE OF REVIEW

The peritoneal membrane provides the interface between dialysate fluid and blood for peritoneal dialysis patients. Functional properties of the peritoneal membrane have important clinical implications. This review will outline recent observations concerning structural changes in the peritoneal membrane and the impact on function and clinical outcomes.

RECENT FINDINGS

Peritoneal membrane function - solute transport and ultrafiltration - is a complex process involving new blood vessel growth along with changes in the nature of blood vessels and the interstitial environment of these vessels. Advanced glycation end-products produced by reactive oxygen species in the dialysis fluid have been identified as an agent of tissue fibrosis. Nitric oxide and IL-6 also have important roles in peritoneal membrane injury. Gene polymorphisms associated with peritoneal membrane function have been identified. As the mechanisms of peritoneal membrane injury become better elucidated, targeted therapies are being developed. The role of biocompatible and nonglucose dialysis fluids needs to be further defined.

SUMMARY

The peritoneal membrane is the lifeline for peritoneal dialysis patients. Our understanding of mechanisms of injury and functional responses continues to expand and will hopefully lead to therapies to improve the clinical outcomes for peritoneal dialysis patients.