Calcitonin test explained
less than 25 pg/ml (numerically the same as ng/l) — MedlinePlus medical encyclopedia: Calcitonin blood test
- Updated
- 2026-09-10
- Every number with its source
What calcitonin is and why it is tested
Calcitonin is a hormone produced by special cells of the thyroid gland called C cells (parafollicular cells). This hormone takes part in calcium metabolism, but in clinical practice calcitonin is tested first of all as a marker that helps detect medullary thyroid cancer — a rare form of thyroid cancer that develops precisely from C cells. Because these cells produce far more calcitonin than usual when they turn malignant or multiply excessively (C-cell hyperplasia), the amount in the blood becomes a sensitive indicator. The test is also used to monitor whether treatment for medullary thyroid cancer is working and whether the tumour has returned after surgery. In addition, it is used to check people whose family has had cases of medullary thyroid cancer or multiple endocrine neoplasia type 2 (MEN 2) syndrome.
Normal values
| Group | Normal value | Source | ||
|---|---|---|---|---|
| Men MedlinePlus medical encyclopedia: Calcitonin blood test | less than 25pg/ml (numerically the same as ng/l) | pg/ml (numerically the same as ng/l) | MedlinePlus Reviewed 2025-04-24 | |
| Women MedlinePlus medical encyclopedia: Calcitonin blood test | less than 20pg/ml (numerically the same as ng/l) | pg/ml (numerically the same as ng/l) | MedlinePlus Reviewed 2025-04-24 | |
According to the MedlinePlus encyclopedia, the normal value for women is usually reported on the laboratory report as less than 20 pg/ml (ng/l), and for men as less than 25 pg/ml (ng/l) — so the limit that applies to men is the higher one. The source states that normal values for women and men can differ, but it does not explain why this is so physiologically. The most important practical conclusion is therefore this: a woman's result has to be compared with the interval for women (up to 20 pg/ml) and not with the limit applied to men, because otherwise the result may look falsely normal; a man's result has to be assessed against the 25 pg/ml limit for men rather than the lower value for women. Because laboratories may use different assay methods, the exact interval can differ slightly, so the range printed on your own report should be treated as the main point of reference.
When calcitonin is tested
- When medullary thyroid cancer or C-cell hyperplasia is suspected — for example, after a thyroid nodule has been found
- After surgery for medullary thyroid cancer — to assess whether the tumour was removed completely and whether it has returned
- To monitor over time how well treatment for medullary thyroid cancer is working
- For family members, when a close relative has been diagnosed with medullary thyroid cancer or MEN 2 syndrome
- When other rare conditions that can raise calcitonin are suspected — for example, certain neuroendocrine tumours
How to prepare
- Most often no special preparation is needed
- Before the test you may have to go without food and drink for a few hours — your doctor or the laboratory will confirm whether this is necessary
- It is worth mentioning to your doctor the medicines you take, because some medicines that reduce stomach acid can affect the result
A raised calcitonin
A raised calcitonin is considered the most important marker pointing to possible medullary thyroid cancer — the most common cause of a raised level. Calcitonin can also be raised by C-cell hyperplasia, by some other tumours (for example lung cancer, insulinoma, VIPoma), by kidney disease, by smoking, by higher body weight, or by certain medicines that reduce stomach acid. The result needs to be discussed with a doctor together with other tests, for example a thyroid ultrasound.
- Medullary thyroid cancer (the most common cause)
- Lung cancer
- Insulinoma or VIPoma (rare forms of endocrine pancreatic tumour)
- Kidney disease
- Smoking and higher body weight
- Some medicines that reduce stomach acid
What usually comes next
- A thyroid ultrasound and a biopsy of the nodule, if the result raises a suspicion of medullary cancer
- Genetic testing for RET gene mutations and MEN 2 syndrome, especially if there is a family history
- A review of kidney function and of the medicines taken as possible causes
- Repeating the test over time to follow the change
A low calcitonin
A low calcitonin level is not dangerous. According to MedlinePlus, it does not cause any known health problems — it is regarded as a normal variant rather than a sign of a disorder.
Related pages
Related pages on this site: TSH, thyroid tests, how to prepare for thyroid tests, free T4 (FT4), free T3 (FT3), thyroglobulin, parathyroid hormone, calcium, and how to read blood test results. Pages under /rodikliai/ are in Lithuanian.
Full site in Lithuanian: proactiva.app
Frequently asked questions
›What is the normal range for calcitonin?
According to the MedlinePlus medical encyclopedia, the normal value is less than 25 pg/ml for men and less than 20 pg/ml for women (numerically the same figures in ng/l). You will always find your laboratory's exact interval on your own report, because methods can differ slightly between laboratories.
›Why is calcitonin tested?
Calcitonin is tested first of all because of medullary thyroid cancer — a rare form of thyroid cancer arising from the hormone-producing C cells. The test helps to detect this disease, to monitor the results of treatment after surgery, and to check whether the tumour has returned.
›What does a raised calcitonin mean?
A raised calcitonin is most often linked to the possibility of medullary thyroid cancer or to C-cell hyperplasia, but it can also be raised by some other tumours, by kidney disease, by smoking or by certain medicines. The result needs to be discussed with a doctor together with other tests, for example a thyroid ultrasound.
›Is a low calcitonin dangerous?
No. According to MedlinePlus, a low calcitonin level does not cause any known health problems — it is regarded as a normal variant rather than a sign of a disorder.
›How should I prepare for a calcitonin test?
Most often no special preparation is needed, but in some cases you may have to go without food and drink for a few hours before the test — this should be checked with your doctor or the laboratory.
›Who is the calcitonin test ordered for because of inheritance?
The test may be ordered for people whose close relative has been diagnosed with medullary thyroid cancer or multiple endocrine neoplasia type 2 (MEN 2) syndrome, because these conditions can be inherited.
Sources
- MedlinePlus enciklopedija: Calcitonin blood test — 2026-09-06
Related markers
This site is not an emergency service. If severe chest or head pain, breathlessness, confusion, difficulty speaking, heavy bleeding or another acute problem has come on suddenly — do not wait for tests, call 112.
This information is not a diagnosis and does not replace a consultation with a doctor. Reference ranges depend on the laboratory, your age and sex — always compare your result with the range printed on your own report.