The effect of renal function on serum levels of CA 125

Objective: Serum assays for CA 125 are used to monitor disease status in patients undergoing treatment for epithelial ovarian cancer. While a number of benign gynecologic as well as benign and malignant nongynecologic conditions are associated with CA 125 elevations, the established 'normal' range describes a healthy population of women. The metabolism and clearance of CA 125 is not well understood. Because mild degrees of renal impairment frequently occur in ovarian cancer patients, we investigated the effect of impaired renal function on basal CA 125 in a population of female dialysis patients. Methods: Twenty-five women on hemodialysis were selected at random. Patients ranged in age from 29 to 87 years. Renal disease was secondary in most cases to diabetes mellitus or hypertension. The creatinine clearance was less than 10 cc/min for all patients. The duration of dialysis ranged from 3 months to 14 years. Serum levels of CA 125 were measured using monoclonal antibodies in an immunoradiometric assay. Results: The mean of duplicate determinations for 23 of 25 (92%) patients fell within the normal range for otherwise healthy women (<35 U/ml). There was no apparent correlation between CA 125 level and age, menopausal status, BUN, serum creatinine, adequacy of dialysis, or primary underlying diagnosis. Of the 2 patients (8%) with CA 125 levels above the normal range, 1 was premenopausal and the other was postmenopausal; their CA 125 elevations were marginal (49.81 and 50.51). Conclusions: The results of this study demonstrate that even marked renal insufficiency is not itself associated with significant elevations of CA 125 above the normal range selected for otherwise healthy women. The development of renal insufficiency during treatment for ovarian cancer should not alter the interpretation of serum levels of CA 125.