Calcitonin (Thyrocalcitonin)
The calcitonin test measures serum calcitonin, a peptide hormone secreted by thyroid parafollicular C cells. Its principal clinical use is detection and monitoring of medullary thyroid carcinoma, where elevated levels correlate with tumour burden. Calcitonin is ordered in the work-up of thyroid nodules suspicious for MTC, in MEN2 syndrome screening, and for post-operative surveillance.
1
Biomarkers
Blood (serum)
Sample
3–5 business days
Turnaround
No
Fasting
What is the Calcitonin test?
The Calcitonin (Thyrocalcitonin) Test measures serum calcitonin, a peptide hormone secreted by thyroid parafollicular C cells. Its clinical application is narrow but critical: detection and monitoring of medullary thyroid carcinoma, a rare neuroendocrine malignancy that produces calcitonin in proportion to tumour burden. Practitioners do not order calcitonin as part of routine thyroid screening; instead, it is reserved for patients with a thyroid nodule and clinical features suggesting MTC, individuals with known or suspected multiple endocrine neoplasia type 2 (MEN2) syndrome, and post-thyroidectomy surveillance of patients with established MTC. The test's high specificity for C-cell pathology makes it a powerful tumour marker, though mild elevations can occur with C-cell hyperplasia, neuroendocrine tumours elsewhere, renal impairment, or certain medications. Calcitonin is typically ordered alongside carcinoembryonic antigen (CEA), which is also elevated in MTC and adds prognostic and monitoring value, and interpreted in the context of thyroid ultrasound and cytology findings.
What does the Calcitonin test measure?
Calcitonin is a 32-amino-acid polypeptide hormone secreted primarily by parafollicular C cells of the thyroid. Its canonical physiological role is inhibition of osteoclast-mediated bone resorption and promotion of renal calcium excretion, although its importance in normal human calcium homeostasis is debated. Serum calcitonin is undetectable or very low in healthy individuals but rises dramatically in conditions characterised by C-cell hyperplasia or malignancy. The hormone is cleaved from a larger precursor, procalcitonin, which itself rises in systemic bacterial infection.
Calcitonin measurement is used almost exclusively to detect and monitor medullary thyroid carcinoma (MTC), a neuroendocrine tumour arising from thyroid C cells that constitutively secretes calcitonin. Elevated basal calcitonin — particularly values above 100 pg/mL — is highly specific for MTC and distinguishes it from the far more common differentiated thyroid cancers. Stimulation testing with pentagastrin or calcium historically improved sensitivity but is rarely performed today. Serial calcitonin is the cornerstone of post-operative surveillance, and persistently elevated or rising levels indicate residual or recurrent disease.
Why is the Calcitonin test ordered?
- Pre-operative evaluation of thyroid nodules when cytology is indeterminate or suspicious and MTC is in the differential, particularly with a family history of thyroid cancer or MEN2
- Screening and surveillance of individuals with known or suspected MEN2A or MEN2B syndrome, where germline RET mutations confer high MTC risk
- Post-operative monitoring of patients with a confirmed diagnosis of medullary thyroid carcinoma to detect residual or recurrent disease
- Investigation of a thyroid nodule in a patient with symptoms suggestive of MTC, such as diarrhoea or flushing (paraneoplastic manifestations)
- Work-up of incidentally discovered thyroid mass with imaging features atypical for papillary or follicular carcinoma
- Evaluation of elevated serum calcium or hypercalcaemia work-up when C-cell pathology is suspected, though calcitonin's role in calcium homeostasis is minimal in humans
- Baseline assessment prior to total thyroidectomy in patients with a nodule concerning for MTC on clinical or radiological grounds
Sample collection and turnaround
Sample type
Blood (serum)
Fasting required
No
Collection method
Venipuncture at patient service centre
Turnaround
3–5 business days
Collection notes
Phlebotomy via LabCorp patient service centre; no special preparation. If stimulation testing (calcium or pentagastrin) is planned, co-ordinate with the laboratory and endocrinology service, as these protocols require timed serial sampling and are not routine.
Specimen requirements
Minimum 1 mL serum in a red-top or gel separator tube. Separate from cells promptly and refrigerate or freeze if not analysed within hours; calcitonin is stable frozen for months. Note the assay platform for serial comparability.
What can affect Calcitonin results?
Gastrin stimulates C-cell calcitonin secretion; chronic PPI use and conditions causing hypergastrinaemia (atrophic gastritis, gastrinoma) can raise basal calcitonin modestly.
Calcitonin is partly cleared renally, so reduced GFR may elevate circulating levels independent of C-cell pathology, typically remaining below thresholds suggestive of MTC.
Some carcinoid tumours, small-cell lung cancer, and other neuroendocrine neoplasms can secrete calcitonin ectopically, producing elevations that mimic MTC; clinical context and imaging localise the source.
Physiological or reactive hyperplasia of C cells (seen in chronic hypercalcaemia, Hashimoto thyroiditis, or as a precursor lesion in MEN2) can modestly raise calcitonin without frank malignancy.
Immunoassays for calcitonin are susceptible to heterophile antibody interference, which can produce falsely elevated or suppressed results; dilution studies or repeat testing with a different platform resolve discordance.
Some reports describe mild calcitonin elevation during pregnancy and lactation, though this is not universally observed and remains below pathological thresholds.
What do Calcitonin results mean?
Elevated
Medullary thyroid carcinoma (values >100 pg/mL are highly suggestive; basal levels correlate with tumour burden and stage), C-cell hyperplasia (modest elevations, often <50 pg/mL), neuroendocrine tumours (carcinoid, small-cell lung), chronic kidney disease (mild elevation), hypergastrinaemia (PPI use, atrophic gastritis), and assay interference. Markedly elevated calcitonin mandates imaging, further endocrine work-up, and surgical consultation.
Normal
A normal basal calcitonin effectively excludes medullary thyroid carcinoma in most scenarios, though rare cases of early or small MTC may present with borderline or normal values. Stimulation testing (where available) can unmask occult C-cell disease in high-risk individuals.
Reduced
Low or undetectable calcitonin is the norm in healthy individuals and carries no clinical significance. Post-thyroidectomy, undetectable calcitonin is the goal and indicates biochemical remission of MTC.
Note: Reference ranges and decision thresholds are assay-dependent; serial results should use the same laboratory and method. Calcitonin must be interpreted with CEA, thyroid imaging, family history, and RET mutation status in MEN2 kindreds. Mild elevations require exclusion of renal impairment, hypergastrinaemia, and non-thyroidal neuroendocrine tumours before attributing to C-cell pathology.
Frequently asked questions
Calcitonin is a 32-amino-acid peptide hormone secreted by parafollicular C cells of the thyroid. Its physiological role is inhibiting bone resorption and promoting renal calcium excretion, though its importance in human calcium homeostasis is limited.
How to access the Calcitonin test
The Calcitonin reference page is free and open to all practitioners. Create a free practitioner account to see pricing, save tests to your list, and generate requisition forms. Verification takes 1–2 business days.
Create Free AccountAbout this page
Published: October 7, 2026
Last reviewed: October 7, 2026
- Wells SA Jr, et al. Revised American Thyroid Association guidelines for the management of medullary thyroid carcinoma. Thyroid. (2015)
- Tuttle RM, et al. Updated American Joint Committee on Cancer/Tumor-Node-Metastasis staging system for differentiated and anaplastic thyroid cancer (eighth edition): what changed and why? Thyroid. (2017)
- Elisei R, et al. Impact of routine measurement of serum calcitonin on the diagnosis and outcome of medullary thyroid cancer: experience in 10,864 patients with nodular thyroid disorders. J Clin Endocrinol Metab. (2004)
- National Comprehensive Cancer Network (NCCN) clinical practice guidelines in oncology: thyroid carcinoma. (2023)
This content is for licensed healthcare practitioners only and does not constitute medical advice. Clinical decisions should be based on the full clinical picture and not on any single test result.
Related tests
cancer biomarkers
CEA
The CEA test measures serum carcinoembryonic antigen, a glycoprotein tumour marker elevated in colorectal, gastric, pancreatic, lung, and breast cancers. It is used to monitor treatment response and detect recurrence in known malignancy, not as a screening tool, since benign inflammatory disease and smoking also raise CEA and many early cancers produce normal levels.
thyroid endocrine
PTH Intact
The Parathyroid Hormone (PTH) Intact test measures biologically active PTH 1-84 in serum, serving as the central biochemical marker of parathyroid gland function and the definitive differentiator of calcium dysregulation aetiology. Elevated PTH with elevated calcium confirms primary hyperparathyroidism;