Reference values — CA-125 (serum)
CA-125 (Cancer Antigen 125) is a nonspecific glycoprotein marker that may be elevated in early pregnancy, postpartum, and a variety of benign or malignant conditions. Physiologic pregnancy-related elevations occur especially in the 1st trimester.
| Units | Nonpregnant Adult | 1st Trimester | 2nd Trimester | 3rd Trimester |
|---|---|---|---|---|
| U/mL | < 35 | 0 – 51.5 | 0 – 30.8 | 0 – 56.3 |
Pregnancy-specific considerations
CA-125 may rise with trophoblastic and decidual activity, uterine stretching, peritoneal inflammation, or immediately postpartum. Normal or low values do not exclude malignancy.
Causes of increased CA-125
- Physiologic pregnancy elevation — highest in 1st trimester and early postpartum
- Endometriosis, adenomyosis
- Uterine fibroids
- Pelvic inflammatory disease
- Benign ovarian cysts
- Renal failure
- Ascites of any origin
- Cirrhosis or chronic liver disease
- Pancreatitis, GI inflammation
- Malignancy — epithelial ovarian cancer, fallopian tube carcinoma, endometrial cancer, cervical adenocarcinoma, GI cancers, lung cancer
- Trophoblastic disease
Causes of decreased CA-125
- Normal pregnancy after 1st trimester (physiologic decline)
- Low peritoneal/endometrial inflammatory activity
- Early ovarian cancer (often normal CA-125)
- Obesity (hemodilution effect)
- Chemotherapy suppressing inflammation
Low CA-125 rarely indicates disease. A normal or low value should not be used to exclude malignancy.
References
- Touitou Y et al. Tumour marker antigens during menses and pregnancy. Br J Cancer. 1989;60:419–420. PMID:2789952.
- Tan MCB et al. Tumor Biology and Tumor Markers. In: Sabiston Textbook of Surgery. WB Saunders; 2007.
- Wallach J. Interpretation of Diagnostic Tests. 8th ed. LWW; 2007.