Pronounced increases in the concentration of an ovarian tumor marker, CA-125, in serum of a healthy subject during menstruation.

CA-125 is a glycoprotein associated with various ovarian tumors. A commercial radioimmunoassay involving a monoclonal antibody is available for it. In our laboratory, a normal-value study was conducted as part of a routine evaluation of this assay. One healthy subject had a serum CA-125 concentration greater than 300 kU/L, more than eightfold the upper limit of normal (35 kU/L). This increase, which coincided with the onset of the menstrual period, subsided to within the normal range by the end of the menstrual cycle. The half-life of CA-125, calculated from this decrease, was 6.4 days. Similar observations were made in the same subject over several menstrual cycles. Results of clinical and ultrasound examinations of the subject for ovarian tumors were negative. No clinical evidence of malignancy was present eight months after the initial discovery of an increased CA-125. None of the other 39 healthy subjects had a CA-125 value greater than 51 kU/L. Five of these subjects had CA-125 determined several times during their menstrual cycles; none exhibited pronounced variations in CA-125 concentrations. Evidently CA-125 can be extremely increased in a healthy woman, and possible effects of the menstrual period on serum CA-125 concentrations should be considered in pre-menopausal patients.