Calcitonin Test
Calcitonin is a hormone produced by the C-cells of the thyroid gland. It is not involved in routine thyroid function, but it is an important tumour marker for medullary thyroid cancer and for the inherited syndromes that cause it.
The test is used selectively, not as part of routine thyroid screening.
Last medically reviewed: 15 November 2025
What it measures
Calcitonin is made by the parafollicular C-cells. A raised level can indicate medullary thyroid cancer, a less common thyroid cancer that arises from these cells.
Levels are also used to monitor people treated for medullary thyroid cancer, where a rising trend may suggest recurrence.
When it is ordered
Calcitonin is checked when a nodule is suspected to be medullary cancer, when there is a family history of medullary thyroid cancer or MEN2 syndrome, and in follow-up after treatment.
Because raised levels can occur in other conditions and with certain medications, results are interpreted carefully by a specialist.
Interpretation and next steps
A clearly raised calcitonin in the right context strongly suggests medullary thyroid cancer and prompts further evaluation, including genetic testing for RET mutations.
Because MEN2 is inherited, a positive genetic result has implications for family members, who may be offered testing and counselling.
Frequently asked questions
Is calcitonin part of a routine thyroid test?
No — it is used selectively when medullary thyroid cancer is suspected, in family screening, or in follow-up after treatment.
What does a raised calcitonin mean?
It can indicate medullary thyroid cancer, but other conditions and some medications can also raise it. Results are interpreted with the full clinical picture.
Should my family be tested?
If medullary thyroid cancer is confirmed or an inherited syndrome is found, close relatives may be offered genetic testing and counselling.
References & further reading
This page is based on established medical knowledge and guidelines from authoritative sources. Always consult a qualified clinician for personal medical advice.
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