Description
Overview: Calcitonin is a hormone produced by the parafollicular cells (C-cells) of the thyroid. In healthy individuals, calcitonin levels are usually very low. Its main biological function involves regulating calcium and phosphorus levels, but in clinical diagnostics, it serves as a highly sensitive marker for abnormal C-cell growth.
Clinical Significance:
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Medullary Thyroid Carcinoma (MTC): This is the most important use of the test. Significantly elevated levels are a strong indicator of MTC.
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Treatment Monitoring: After the removal of the thyroid gland (thyroidectomy) for cancer, calcitonin levels should fall to undetectable levels. Rising levels indicate a recurrence of the cancer.
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Family Screening: It is used to screen family members of patients with MEN2 (a genetic syndrome) to detect MTC in its earliest, most treatable stages.
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C-Cell Hyperplasia: Elevated levels can also be seen in benign overgrowth of C-cells, often a precursor to cancer.
When is this test recommended?
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To evaluate a patient with a thyroid nodule or lump.
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To screen patients with a family history of thyroid cancer or MEN2.
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To monitor patients who have been treated for Medullary Thyroid Cancer.
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When a patient presents with symptoms of advanced MTC, such as unexplained diarrhea or facial flushing.
Sample Requirements:
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Specimen: Serum.
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Container: Gold Top (SST) or Red Top Tube.
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Preparation: Fasting (overnight) is typically required to get an accurate baseline level.
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Handling: This hormone is unstable; the sample often needs to be kept cold (on ice) and processed immediately.
