Background and objectives: Medullary thyroid carcinoma (MTC) originates from thyroid C-cells and is a calcitonin (CT) secreting tumour with aggressive behaviour. Surgery is recommended in all patients with basal or calcium-stimulated CT values of 100 pg/ml or higher due to the high probability of MTC. The objective of this study was to investigate the utility of calcium stimulation test for CT in order to distinguish MTC from C-cell Hyperplasia (CCH) preoperatively and to examine the histological findings of thyroidectomy in patients with peak stimulated CT >100 pg/ml.
Patients and methods: A total of 52 patients with thyroid nodules and basal CT levels between 6 and 100 ng/l had a positive calcium stimulation test (peak CT >100 ng/l) and underwent total thyroidectomy.
Results: patients (35%) were diagnosed with MTC and 34 (65%) with CCH. 20 patients (38%) had a differentiated carcinoma of follicular origin (DTCf) coexistent with either MTC or CCH. Calcium-stimulated calcitonin levels >452 ng/l had the optimal sensitivity and positive predictive value for differentiating MTC from CCH.
Conclusion: A large percentage of MTC may be identified by peak stimulated CT levels >100 pg/ml preoperatively, but overlapping calcitonin levels between MTC and CCH reduce the accuracy of the test. Remarkably, many patients with peak stimulated CT levels >100 pg/ml harbour a DTCf. A probable association between C-cell disease and DTCf needs further examination.
16 - 20 May 2015
European Society of Endocrinology