Serum CA125 a potential marker of volume status for peritoneal dialysis patients?

Introduction: Serum cancer antigen 125(SeCA125) has been reported to be increased in patients with heart failure and correlate with both extracellular water (ECW) overload and poor prognosis. Ultrafiltration failure and ECW overload are a major cause of peritoneal dialysis (PD) technique failure. We wished to determine whether SeCA125 could also be a marker of volume status in PD patients. Methods: We contemporaneously measured SeCA125, serum N terminal brain natriuretic peptide (NTproBNP) and ECW by bioimpedance in adult PD patients attending for outpatient assessment of peritoneal membrane function. Results: The median SeCA125 was 19 (12-33) U/mL in 489 PD patients, 61.3% male, median age 61.5 (interquartile range 50-75) years. SeCA125 was positively associated with the ratio of ECW/total body water (TBW) (r = 0.29, p < 0.001), 4-h peritoneal dialysate to serum creatinine ratio (r = 0.23, p < 0.001), NTproBNP) (r = 0.18, p < 0.001), and age (r = 00.17, p = 0.001) and negatively with 24-h PD ultrafiltration volume (r = -0.28, p < 0.001) serum albumin (r = -0.22, p < 0.001), and echocardiographic left ventricular ejection fraction (r = -0.20, p < 0.001), but not with residual renal function or C-reactive protein. Patients with above the median SeCA125, had greater median ECW/TBW 0.403(IQR 0.394-0.410) vs 0.395(0.387-0.404), p < 0.001 and NTproBNP (6870 (IQR 1936-20096) vs 4069 (1345-12291) vs) pg/mL, p = 0.03. Conclusion: Heart failure studies have reported SeCA125 is a marker of ECW overload. Our retrospective analysis suggests that SeCA125 is also associated with ECW volume in PD patients. Further studies are required to determine whether serial measurements of SeCA125 trend with changes in ECW status in PD patients and can be used to aid volume assessments.