Health Encyclopedia

Calcitonin

Does this test have other names?

Human calcitonin, HCT, thyrocalcitonin

What is this test?

This test measures the level of calcitonin in your blood. Calcitonin is a hormone secreted by the thyroid. The thyroid, a butterfly-shaped gland in the neck, makes hormones that control metabolism.

Why do I need this test?

You may need this test if you have symptoms of medullary thyroid cancer, such as a lump or swelling in your neck.

If you've been diagnosed with thyroid cancer, your doctor can use this test to see how well cancer treatment is working or check if the cancer has come back.

This test is also used as a screening test for people with a family history of medullary thyroid cancer. Screening lets you know more about your risk for developing the cancer and indicates whether you should take additional steps. The earlier cancer is found, the better your chances of survival.

You also might have this test if your doctor suspects you have C-cell hyperplasia, a benign thyroid disease that also runs in families.

What other tests might I have along with this test?

You may also have a blood test to measure the amount of calcium in your blood.

People with medullary thyroid cancer are likely to have high levels of a protein called carcinoembryonic antigen (CEA) in their blood. Blood tests for CEA can sometimes help health care providers diagnose this cancer.

What do my test results mean?

Many things may affect your lab test results. These include the method each lab uses to do the test. Even if your test results are different from the normal value, you may not have a problem. To learn what the results mean for you, talk with your health care provider.

Calcitonin is measured in picograms per milliliter (pg/mL). Normal results are:

  • 19 pg/mL or less for men

  • 14 pg/mL or less for women

Increased levels of calcitonin could mean that you have medullary thyroid cancer or that your cancer has returned. Decreasing levels mean your tumor is shrinking.

Having cancer of the breast, lung, or pancreas can also increase levels.

How is this test done?

The test requires a blood sample, which is drawn through a needle from a vein in your arm.

Does this test pose any risks?

Taking a blood sample with a needle carries risks that include bleeding, infection, bruising, or feeling dizzy. When the needle pricks your arm, you may feel a slight stinging sensation or pain. Afterward, the site may be slightly sore.

What might affect my test results?

Other conditions can cause elevated levels of calcitonin. These include:

  • Being pregnant

  • Taking certain drugs including oral contraceptives, epinephrine, glucagon, and calcium

How do I get ready for this test?

You will probably have to fast starting at midnight before your test. Ask your doctor if it's okay to drink water.  Be sure your doctor knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illicit drugs you may use.