Calcitonin Test

A calcitonin test measures the level of calcitonin in a sample of your blood. Calcitonin is a hormone that helps control the level of calcium in your blood. Calcitonin is made in your thyroid gland by cells called 'C cells.' Your thyroid is a small, butterfly-shaped gland in your neck.

Normally, you have a small amount of calcitonin in your blood. But if you have too much, it may be a sign of: Medullary thyroid cancer (MTC), a rare cancer that happens when C cells in your thyroid grow out of control. C cells grow in the inside part of your thyroid, which is called the medulla.; C-cell hyperplasia, a rare condition that causes abnormal growth of C cells in your thyroid.

C-cell hyperplasia can turn into medullary thyroid carcinoma.; Your health care provider may order a calcitonin test if you have symptoms of these conditions or if they run in your family.

Why this test is done

You may need a calcitonin test to help check for medullary thyroid cancer or C-cell hyperplasia if:

• You have symptoms of either condition which may include:
• A lump in the front of your neck
• Swollen lymph nodes in your neck (also called "swollen glands")
• Pain in your throat
• Trouble swallowing or breathing
• A change in your voice, such as hoarseness
• A long-lasting cough when you don't have a cold
• Diarrhea
• You have symptoms of multiple endocrine neoplasia type 2 (MEN 2). MEN 2 can affect your thyroid, adrenal, and parathyroid glands. Symptoms depend on which glands are affected. They may include:
• Fatigue
• Depression
• Aches and pains in bones and joints
• Nausea and vomiting
• Increased thirst and urination (peeing)
• High blood pressure
• Headaches
• Arrythmia (a problem with the rate or rhythm of your heart)
• Sweating
• You have a family history of MEN 2, which increases your risk of developing medullary thyroid cancer. If MEN 2 runs in your family, you and your family members, including children, may need regular calcitonin tests to help find cancer before you have symptoms. Your provider may also suggest a blood test to check for changes in your RET genes that cause MEN 2.

If you've been diagnosed with medullary thyroid cancer, you'll need calcitonin testing to:

• Find out how well your treatment is working.
• Check whether the cancer has come back after you finish treatment.

How to prepare

You may need to fast (not eat or drink) for several hours before the test. Your provider will let you know if you need to fast and if there are any special instructions to follow.

Sample type

Blood

Other names for this test

thyrocalcitonin, CT, human calcitonin, hCT