CA-125 blood test

CA-125 Blood Test

A CA-125 blood test is a test used to measure the amount of the protein CA-125 in the blood. CA-125 is a tumor marker, meaning it’s released into the bloodstream by cells of certain types of cancer. Since tumor markers such as CA-125 can be useful in diagnosing and monitoring certain types of cancer, CA-125 tests are frequently used for cancer screening.


  • Gynecologic cancers
  • Lung cancer
  • Pancreas cancer
  • Colorectal cancer
  • Kidney cancer
  • Other types of cancers, such as prostate, breast, and ovarian cancers.

When to Perform?

Your doctor may recommend a CA-125 test if you have signs and symptoms that could be related to cancer, are at risk of certain types of cancer or as a follow-up test after a diagnosis of cancer has been made. It may also be recommended after a cancer diagnosis to monitor how well treatment is working. You may need to have more than one CA-125 test over time.

Preparations and Procedure

A CA-125 blood test is a simple procedure. You will typically be asked to refrain from eating or drinking anything but water for about eight hours before the test. Your doctor or technician will take a sample of your blood. The blood sample is usually taken from a vein in your arm. Once the blood is collected, it will be sent to a lab for testing. Your doctor will give you instructions on when to expect the results.


CA-125 tests are safe and noninvasive. There is a small risk of minor bleeding, bruising, or discomfort. For those who have a needle phobia, a topical numbing agent can usually be used to reduce discomfort.


A CA-125 test can help diagnose various types of cancer and can provide valuable information about the stage of the cancer. The test is not used in isolation to diagnose cancer; it is typically paired with other diagnostic tests such as ultrasound, MRI, and biopsy. It can also help to monitor the cancer’s progress and response to treatment. Additionally, it is sometimes used to detect the presence of cancer recurrence.

Normal Levels

The normal reference range for CA-125 is 0–35 U/mL (units per milliliter). Some healthy individuals may have levels above this range. In general, any level above 35 U/mL requires further investigation. Your doctor will consider various factors, such as your age, medical history, and background risk for cancer, to determine if further testing or treatment is needed.


A CA-125 blood test is a helpful tool for diagnosing and monitoring certain types of cancers. While relatively straightforward, it is important to work with your doctor to decide if a CA-125 test is right for you. Knowing your results and discussing them with your doctor are both crucial steps to maintaining good health.