Evaluation of changes in serum and dialysate levels of cancer antigen 125 in stable continuous ambulatory peritoneal dialysis patients.

To estimate the relationship between changes in the concentration of cancer antigen 125 (CA125) and peritoneal membrane kinetics, the permeability characteristics of 44 continuous ambulatory peritoneal dialysis (CAPD) patients who had been treated with peritoneal dialysis for at least six months were prospectively evaluated. Twenty-seven males (age 66 +/- 6 years, duration of CAPD 35.5 +/- 29 months) and seventeen females (age 63.7 +/- 9 years, duration of CAPD 47.7 +/- 32 months) were evaluated. Peritoneal equilibration test (PET) data and Adequest (Baxter Healthcare Corporation, Deerfield, Illinois, U.S.A.) data were analyzed in all patients over a 12-month period, while CA125 levels were measured in blood and dialysate samples. No statistically significant correlations were seen between the patients' age, sex, or peritonitis incidence rates, and serum and dialysate levels of CA125. Dialysate-to-plasma ratio (D/P) of small solutes at 0 and 240 minutes also showed no statistical correlation. Statistical analysis revealed a statistically significant negative correlation (r = -0.33, p = 0.035) between dialysate CA125 and duration of CAPD. The statistically significant difference found between dialysate CA125 concentrations at 0 minutes and 240 minutes (2.32 +/- 1.3 U/mL vs 9.08 +/- 6.8 U/mL, p < 0.0001), means that CA125 concentration increases with longer dwell time. These results suggest that the duration of CAPD clearly affects dialysate CA125 concentrations. CA125 may therefore be used as a useful marker to evaluate the mesothelial cell mass in longitudinal follow-up.