Calcitonin is a hormone that is mainly produced by the C cells (parafollicular cells) of the thyroid gland. The hormone plays a role in the body's calcium and phosphate metabolism by inhibiting bone resorption and lowering calcium levels in the blood. In healthy adults, calcitonin has relatively limited physiological significance, but it is an important biomarker in the diagnosis of certain endocrine tumors, especially medullary thyroid cancer.
Calcitonin is clinically valuable in suspected medullary thyroid cancer, but elevated concentrations can also occur in other neuroendocrine tumors such as pheochromocytoma, endocrine pancreatic tumor and endocrine intestinal tumor. The analysis is used both for diagnosis, monitoring after treatment and in genetic screening of families with hereditary medullary cancer (MEN2 syndrome).
What can cause an elevated calcitonin level?
An elevated calcitonin level is often a sign of pathological conditions, especially tumors originating from neuroendocrine cells. Here are some causes of elevated calcitonin levels:
Medullary thyroid cancer: The most important clinical cause of high calcitonin. Elevated levels are seen in both sporadic and hereditary forms of this cancer.
Pheochromocytoma: A hormone-producing tumor in the adrenal medulla that can cause elevated calcitonin in the presence of MEN2 syndrome.
Endocrine pancreatic tumors: Some neuroendocrine tumors in the pancreas can cause elevated calcitonin.
Endocrine intestinal tumors: Tumors of the gastrointestinal tract that produce hormonal substances, including calcitonin.
Renal failure: In chronic renal failure, calcitonin levels in the blood may be slightly elevated, indicating that the kidneys have a reduced ability to eliminate the hormone from the bloodstream. In addition, some patients with renal failure may develop secondary hyperparathyroidism and disturbed calcium-phosphate balance, which may indirectly affect calcitonin production.
Symptoms of high calcitonin
Elevated calcitonin levels themselves rarely cause direct symptoms, but can indicate underlying diseases with their own characteristic signs:
- Thyroid nodule (in medullary thyroid cancer)
- Sweating, palpitations, headache (in pheochromocytoma)
- Diarrhea and abdominal pain (can be seen in certain endocrine tumors)
- Nervousness, high blood pressure (associated with neuroendocrine syndromes)
Note that the symptoms depend on the type and extent of the underlying tumor, not on the calcitonin itself.
What can a low calcitonin value mean?
Low concentrations of calcitonin are normal and usually have no clinical significance. In contrast, low or undetectable levels after surgical treatment of medullary thyroid cancer are a good indication that the disease is under control or in remission.
After thyroidectomy: After removal of the thyroid gland, the source of calcitonin disappears, leading to very low levels.
No detectable disease: Normal or low values usually indicate the absence of neuroendocrine tumors.
Other effects of calcitonin
Although calcitonin in humans is not essential for calcium regulation, it acts by inhibiting osteoclast activity in the skeleton, thereby reducing bone resorption. It may therefore play some role in bone metabolism, especially in conditions of elevated calcium. In medical therapy, synthetic calcitonin is sometimes used to treat conditions such as osteoporosis, hypercalcemia, and Paget's disease, although its use has declined due to better alternatives.
Reference range for S-CalcitoninMen: below 3.5 pmol/L
Women: below 1.5 pmol/L
Interpretation in tumor diagnostics
Values above 20 pmol/L are strongly suspected of medullary thyroid cancer and should be investigated further. In the case of slightly elevated levels between 5–10 ng/L, follow-up, stimulation tests and additional imaging diagnostics may be necessary to rule out tumor.