Cancer Antigen 125 (CA 125)
Other marker
CA 125
Cancer Antigen 125 (CA 125)
A protein (MUC16) shed from certain epithelial surfaces, used chiefly as a tumour marker for monitoring epithelial ovarian and peritoneal cancer. It is reported in kIU/L (numerically equivalent to the older U/mL). It is primarily a female-relevant marker.
PED Notes
CA 125 is mainly a female marker: its established role is monitoring known ovarian or peritoneal cancer and following treatment response, not general screening. It has poor specificity, being raised by many benign conditions in women, including menstruation, endometriosis, ovarian cysts, pelvic inflammation, pregnancy, and any cause of peritoneal irritation or ascites. Because of that, it is not a useful screen in people at average risk. In men it has very limited relevance and is only occasionally elevated (for example with peritoneal or pleural inflammation, liver disease with ascites, or heart failure); it appears here because broad wellness panels sometimes include it. For enhanced athletes there is no meaningful PED-specific interpretation. Any genuinely elevated or rising value should be assessed clinically rather than self-interpreted.
When high
When CA 125 is elevated:
- Interpret in clinical context, not in isolation. In women it is elevated by many benign conditions (menstruation, endometriosis, ovarian cysts, pelvic inflammation, pregnancy) as well as by ovarian/peritoneal malignancy.
- It is not a validated screening test for average-risk individuals; a single mildly raised value in an asymptomatic person often reflects a benign cause.
- A persistently elevated or rising level, or elevation with symptoms (bloating, pelvic pain, abdominal distension), warrants medical assessment, typically pelvic imaging and specialist referral.
- In men, any significant elevation is non-specific and should prompt evaluation for causes of serosal irritation or ascites (liver disease, heart failure, pleural/peritoneal processes) rather than being ignored or over-interpreted.
History Chart
Reading History
Frequently Asked Questions
Reference Ranges
Standard Range
VitalMetrics Range