Calcitonin

Human calcitonin, hCT, thyrocalcitonin

This test measures how much calcitonin is in your blood. Calcitonin is a hormone made by the thyroid. The thyroid is a butterfly-shaped gland in your neck. It makes hormones that control metabolism.

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

If you've been diagnosed with thyroid cancer, your healthcare provider can use this test to see how well cancer treatment is working. They may also use this test to 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 of developing the cancer. It lets you know 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 healthcare provider thinks you have C-cell hyperplasia. This is a benign thyroid disease that runs in families.

Medullary thyroid cancer can affect calcium levels. So 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 healthcare providers diagnose this cancer.

Test results may vary depending on your age, gender, health history, and other things. Your test results may be different depending on the lab used. They may not mean you have a problem. Ask your healthcare provider what your test results mean for you.

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

• 8.4 pg/mL or less for men

• 5.0 pg/mL or less for women

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

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

The test is done with a blood sample. A needle is used to draw blood from a vein in your arm or hand. 

Having a blood test with a needle carries some risks. These include bleeding, infection, bruising, and feeling lightheaded. When the needle pricks your arm or hand, you may feel a slight sting or pain. Afterward, the site may be sore. 

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

• Being pregnant

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

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