Calcitonin

Immunology

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Description

The main application of all tumour markers is monitoring for relapse or progression. Use as a diagnostic aid requires care and knowledge of the test limitations. Opportunistic screening is discouraged. Serum calcitonin measurement is used in the primary clinical assessment of medullary thyroid carcinoma (MTC). Current guidelines recommend calcitonin plus fine needle aspiration cytology to be the initial investigations performed when evaluating suspected MTC [1,3]. Moderate hypercalcitonemia can be observed in pregnancy, pernicious anaemia, renal failure and during the neonatal period. Medullary thyroid carcinoma (MTC) is a malignant tumor, developed from the C-cells, secreting calcitonin in large excess. This disease occurs either as a sporadic (75%) or an hereditary (25%) form, which is transmitted as an autosomal dominant gene or as a component of multiple endocrine neoplasia (MEN) [2]. Medullary carcinoma of the thyroid accounts for 5-10% of all thyroid neoplasms. More modest elevations of calcitonin may be seen in, or induced, in C-cell hyperplasia which may itself be a precursor of medullary carcinoma [4]. Calcitonin is a 32 amino acid peptide hormone secreted by the para-follicular C-cells of the thyroid gland under serum calcium control [2]. Various forms of calcitonin may be detected in blood samples including monomeric, an oxidized monomer, dimeric, higher molecular weight forms, and possibly a precursor of calcitonin. Only the monomeric form is detected in this assay.

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Indications

1. Monitoring medullary carcinoma of the thyroid. 2. Can be used as a screening test in cases that are of familial origin, although this has been superseded by mutational genetic analysis. 3. Screening in Multiple Endocrine Neoplasia (MEN II).

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Sample Type

2mL Serum (6ml Red tube) or 2mL EDTA Plasma. The sample MUST be separated within 30mins of venesection. Requests from outside Sheffield: Transport at ambient temperature via Royal Mail or Courier (dry ice not required).

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Reference Range

< 2 mIU/L.

Reference range established by internal validation of the manufacturers information.

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Turnaround Time

Within 2 weeks

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Testing Frequency

Weekly

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External Notes

In a pentagastrin stimulation test the correct labelling of the tubes with their time sequence is critical

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References

Sturgeon CM and Diamandis EP. Use of tumour markers in clinical practice: Quality requirements. The National Acadamy of Clinical Biochemistry. Laboratory medicine practice guidelines. 2009. [Ref 1]
Sturgeon CM et al. Serum Tumour Markers: How to order and interpret them. British Medical Journal. 2009; 339; 852-858.
Elisei R. Routine serum calcitonin measurement in the evaluation of thyroid nodules. Best Practice & Research Clinical Endocrinology & Metabolism. 2008. 22:941-953. [Ref 2]
Royal Collage of Physicians. Guidelines for the management of thyroid cancer. British thyroid association. 2007. 2nd Edition. [Ref 3]
Leboulleux S, et al. Medullary thyroid carcinoma. Clin Endocrinol. 2004. 61(3):299-310. [Ref 4]

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