CA-125
CA-125 is a protein found on the surface of many ovarian cancer cells and in some normal tissues. This test measures CA-125 levels and is used to monitor ovarian cancer treatment and recurrence.
Category: Tumor Markers
Also known as: ca-125, ca 125, cancer antigen 125
Reference range: 0–35 U/mL (Source: ABIM)
Standard unit: U/mL
High values may indicate
High CA-125 levels may indicate ovarian cancer, endometriosis, pelvic inflammatory disease, uterine fibroids, liver cirrhosis, or pregnancy.
Low values may indicate
Low CA-125 levels are normal and may indicate a good response to cancer treatment in patients being monitored.
Frequently asked questions
- What is a normal CA-125 level?
- A typical reference range for CA-125 is 0–35 U/mL (source: ABIM). Reference ranges vary by laboratory, age, and sex, so always compare against the range on your own lab report.
- What units is CA-125 measured in?
- CA-125 is most commonly reported in U/mL. Labs in different countries may use other units — you can convert between them with BloodId's blood test unit converter.
- Where do CA-125 reference ranges come from?
- BloodId uses ABIM standard reference ranges and educational information from MedlinePlus (see our methodology). Reference ranges still vary by lab, age, and sex, so always compare against your own report.
- Can I track CA-125 over time?
- Yes. Upload results from any lab and BloodId charts your CA-125 over time against its reference range, so you can see whether the trend is rising, falling, or stable.