Cancer antigen 125 (CA125) is a mesothelial product that has been directly related with mesothelial bulk in peritoneal dialysis (PD) patients. Here, we evaluate CA125 levels in peritoneal effluent over time on PD, and relate them to changes in peritoneal function. We analyzed 27 peritoneal kinetic studies in 20 stable PD patients. Three patients dropped out of PD for peritoneal membrane failure after the last kinetic study, and six patients required a peritoneal rest period as treatment for membrane failure type 1. We recorded the standardized daily ultrafiltration capacity, net ultrafiltration during the kinetic study, peritoneal mass transfer coefficients, time from onset of PD, and incidence of peritonitis prior to the study. A linear increase in CA125 levels over time was observed, and a strong correlation appears among the levels at different dwell times (r: 0.85 - 0.98. p < 0.05). At 180 minutes, the mean CA125 concentration was 48.5 +/- 39.7 U/mL. We observed significant differences in CA125 levels in effluent between the group of patients who later required a peritoneal rest period and the group of stable patients (27.7 +/- 26.3 U/mL vs 55.7 +/- 41.5 U/mL, p < 0.05). Patients who left PD showed lower CA125 levels in effluent (31.4 +/- 30.6 U/mL vs 52.3 +/- 41.1 U/mL, p < 0.1). No correlation was seen between CA125 levels in effluent and time on PD, episodes of peritonitis, accumulated days of peritoneal inflammation, ultrafiltration capacity, or urea and creatinine mass transfer coefficients (MTCs). In conclusion, we believe that serial determinations of peritoneal effluent CA125 levels may help in the early identification of patients who show abnormal responses to peritoneal dialysis or its complications.
