Test Details
Methodology
Immunochemiluminometric assay (ICMA)
Result Turnaround Time
3 - 5 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Use
Detection and confirmation C-cell hyperplasia (the precursor of medullary carcinoma of thyroid) as well as a tumor marker for diagnosis and management of medullary carcinoma of the thyroid gland. Preoperative serum calcitonin is reported to roughly correlate with tumor weight or extent of disease; therefore, postoperative levels also have prognostic application. The doubling time of serum levels correlates with a recurrence.1 Multiple endocrine neoplasia (MEN) type II includes medullary carcinoma of the thyroid, hyperparathyroidism, and pheochromocytoma (Sipple syndrome). MEN type IIB includes medullary carcinoma of the thyroid, pheochromocytoma, mucosal neuromas, marfanoid habitus, and intestinal ganglioneuromatosis.2 An important use of calcitonin assay is in follow-up of patients with medullary carcinoma and work-up of their families to detect early, subclinical cases. Indications for calcitonin assay include family history of unspecified type of thyroid cancer, calcified thyroid mass, thyroid tumor associated with hypercalcemia and/or pheochromocytoma, amyloid-containing metastatic carcinoma with unknown primary site and the presence of mucosal neuromas.3
Special Instructions
State on the request form if calcium infusion or pentagastrin injection tests are part of the patient preparation.
Values obtained with different assay methods should not be used interchangeably in serial testing. It is recommended that only one assay method be used consistently to monitor each patient's course of therapy. This procedure does not provide serial monitoring; it is intended for one-time use only. If serial monitoring is required, please use the serial monitoring number 480103 to order.
Limitations
In a number of patients with medullary carcinoma of the thyroid (especially those with familial medullary carcinoma of thyroid) the baseline calcitonin may be normal; however, an abnormally large calcitonin response may follow provocative infusion of calcium and/or pentagastrin4 (usually 3 to 20 times baseline). Most subjects with microscopic medullary carcinoma and all with C-cell hyperplasia have normal basal calcitonin levels; provocative testing is needed (see the online Endocrine Appendix: Calcium-Pentagastrin Stimulation). Occasional spurious high results are encountered. Hemolysis can cause spurious high levels. Calcitonin in patients' sera lacks immunoreactive uniformity. Calcitonin is not a screening test.
Custom Additional Information
High concentrations of calcitonin occur not only in patients with malignant parafollicular or C-cell tumors (medullary thyroid carcinoma), but also in many patients with carcinomas of the lung; in some individuals with carcinoma of breast, carcinoids, islet cell tumors, apudomas, in patients with pancreatitis, thyroiditis and in renal failure. Hypergastrinemia may account for calcitonin elevations in the Zollinger-Ellison syndrome and in pernicious anemia. Medullary carcinoma arises from thyroid C cells (parafollicular cells). C-cell hyperplasia is a preneoplastic state in patients with MEN. Provocative tests that may be used for diagnosis of medullary thyroid carcinoma are pentagastrin and calcium infusion.3 A combined calcium pentagastrin test is described in the see the online Endocrine Appendix: Calcium-Pentagastrin Stimulation.2,3 These tests are much more useful than random plasma levels of calcitonin for the diagnosis of MCT. Early diagnosis of medullary carcinoma of thyroid is needed; total thyroidectomy is curative if the tumor is treated early. Medullary carcinomas of the thyroid gland have a variable histologic picture. Correlation between serum calcitonin levels and immunoperoxidase staining of the neoplastic thyroid tissue for calcitonin may assist in confirming the diagnosis in difficult cases. The direct manifestation of high calcitonin levels is secretory diarrhea in 30% of patients with medullary thyroid carcinoma.
Specimen Requirements
Specimen
Serum, frozen
Volume
1 mL
Minimum Volume
0.4 mL (Note: This volume does not allow for repeat testing.)
Container
Red-top tube or gel-barrier tube
Collection Instructions
Separate serum from cells. Transfer the serum into a LabCorp PP transpak frozen purple tube with screw cap (LabCorp N° 49482). Freeze immediately and maintain frozen until tested. To avoid delays in turnaround time when requesting multiple tests on frozen samples, please submit separate frozen specimens for each test requested.
Stability Requirements
Temperature | Period |
|---|---|
Room temperature | Unstable |
Refrigerated | Unstable |
Frozen | 90 days |
Freeze/thaw cycles | Stable x3 |
Reference Range
Male: 0.0−8.4 pg/mL; female: 0.0−5.0 pg/mL
Storage Instructions
Freeze.
Patient Preparation
Patient should be fasting.
Causes for Rejection
Gross hemolysis; specimen not received frozen; lipemia; plasma specimen
References
Footnotes
LOINC® Map
| Order Code | Order Code Name | Order Loinc | Result Code | Result Code Name | UofM | Result LOINC |
|---|---|---|---|---|---|---|
| 004895 | Calcitonin, Serum | 1992-7 | 004896 | Calcitonin, Serum | pg/mL | 1992-7 |
| Order Code | 004895 | |||||
| Order Code Name | Calcitonin, Serum | |||||
| Order Loinc | 1992-7 | |||||
| Result Code | 004896 | |||||
| Result Code Name | Calcitonin, Serum | |||||
| UofM | pg/mL | |||||
| Result LOINC | 1992-7 |