Calcitonin Test
Reviewed
This test measures the level of calcitonin in your blood. Calcitonin is a hormone made by C cells in the thyroid gland that helps control blood calcium. A high calcitonin level can be a sign of medullary thyroid cancer or C-cell hyperplasia, but it may also be caused by other conditions. The test is used to help diagnose these conditions, monitor treatment, check for cancer recurrence, and screen people at high risk (such as those with a family history of MEN2).
Preparation and collection
You may need to fast (not eat or drink) for several hours before the test. Follow any specific instructions from your provider.
Understanding this test
Use the reference interval and units printed by the laboratory that performed the test. A result outside that interval is not a diagnosis by itself, and a result inside it does not rule out every condition. Your symptoms, history, medicines, timing, and related tests can change what the result means.
- A normal calcitonin level does not rule out medullary thyroid cancer or C-cell hyperplasia, because these conditions do not always cause high calcitonin.
- A high calcitonin level can be caused by other conditions, including certain other cancers, some medicines, and pregnancy. Therefore, a high level alone is not a diagnosis; your provider will consider other test results.
- There is no known medical problem associated with a low calcitonin level.
- For screening, the test is most useful in people with a family history of multiple endocrine neoplasia type 2 (MEN2) and may be repeated regularly.
What to do next
Your provider will interpret your calcitonin levels in the context of your symptoms, medical history, and other test results. If you are being monitored for medullary thyroid cancer, changes in calcitonin over time guide treatment decisions. A calcitonin stimulation test (with IV medicine) may be ordered for more accuracy.