BACKGROUND: Encapsulated peritoneal sclerosis (EPS) is a serious complication in patients undergoing peritoneal dialysis (PD). Neutral-pH dialysate is associated with less peritoneal damage and a lower incidence of EPS than conventional PD solution. However, monitoring for peritoneal damage and predicting EPS remain important during PD therapy. METHODS: We measured the mesothelial cell area, dialysate-to-plasma ratio of creatinine after 4 h, and concentrations of the potential biological markers effluent fibrin degradation products (eFDPs), cancer antigen-125, and interleukin-6 in the effluent dialysate from patients who had been undergoing PD therapy for >
5 years in our hospital. These biomarkers were obtained from the drainage fluid of the final measurement of peritoneal equilibration testing before withdrawal from PD therapy. The concentrations of these potential biomarkers were measured in 39 patients who withdrew from PD therapy and were enrolled in the study. RESULTS: Three participants developed EPS after withdrawing PD. The dialysate-to-plasma ratio of creatinine, area of mesothelial cells, and interleukin-6 appearance rate in participants who developed EPS tended to be higher than those in patients who did not, but there were no significant differences. Significantly more eFDPs were in participants who developed EPS than in those who did not (138.5 ± 15.1 vs. 32.9 ± 7.4 µg/mL, P = 0.002). There was no difference in the cancer antigen-125 appearance rate between the groups. A cut-off value of eFDPs ≥ 119.1 µg/mL was optimal for predicting EPS (P = 0.006, specificity = 0.972, sensitivity = 1.000). CONCLUSION: This study shows that eFDPs may be a useful biological marker for predicting EPS in patients undergoing PD using neutral-pH dialysate.