What does the Calcitonin test measure?

Why is Calcitonin measured?

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.

Reference ranges

Standard reference

Typically <10 pg/mL in women and <15 pg/mL in men on modern two-site immunoassays, with sex-specific partitioning.

Functional medicine optimal

In the absence of MTC, undetectable or low single-digit values are typical. There is no evidence-based 'optimal' calcitonin for health; the metric's utility is dichotomous — normal versus elevated suggesting C-cell disease.

Units

pg/mL, ng/L, pmol/L

Reference ranges vary by laboratory and assay platform. Interpret in context of the issuing laboratory's stated range.