Separate and freeze as soon as possible. Allow the sample to clot and centrifuge at 4°C.
Send to Waikato Hospital frozen
Diagnostic Use and Interpretation:
Tumour marker for medullary thyroid carcinoma (MTC). Elevated calcitonin can occur in patients without medullary thyroid tumours. An unpublished European review of 1200 subjects shows that basal calcitonin elevation to can occur in:
Chronic renal failure < 100 ng/L
Hyperparathyroidism < 25 ng/L
Paget's disease < 25 ng/L
Other tumours (e.g. lung, pancreas) < 250 ng/L
Is medullary thyroid carcinoma sporadic or familial?
The presence of RET proto-oncogene germ line mutations that predispose to this tumour can be detected in peripheral blood by the LabPlus Molecular Genetics Department (contact via Lablink ). Peripheral blood DNA should be analysed in the patient with MTC. If the family history is negative and the patient presenting with apparently sporadic MTC does NOT have an identifiable mutation in peripheral blood DNA, then there is little or no likelihood (100 ng/L is a positive result, but does not distinguish between MTC and C-cell hyperplasia.
A peak level <80 makes the likelihood of MTC remote.