CA125 is one of the tumor indicators. To understand why CA125 is elevated during menstruation, it is important to be clear under what circumstances CA125 will be elevated. Generally CA125 is elevated in two conditions, one is in pathological conditions and the other is in physiological conditions. In pathological cases, CA125 is elevated in ovarian tumors, especially in epithelial ovarian tumors, and in malignant ovarian epithelial tumors, CA125 is elevated in the thousands or hundreds. Another physiological condition, during menstruation or lactation, CA125 will be slightly higher than normal, but the high degree will not be great, generally below 100 U/ml. Therefore, it is generally best to avoid menstruation as an indicator of tumor detection, so that the influence of physiological period can be avoided, causing errors in test results.