The role of serum
calcitonin as part of the evaluation of
thyroid nodules has been widely discussed in literature. However there still is no consensus of measurement of
calcitonin in the initial evaluation of a patient with
thyroid nodule. Problems concerning cost-benefit, lab methods, false positive and low prevalence of medullary
thyroid carcinoma (MTC) are factors that limit this approach. We have illustrated two cases where serum
calcitonin was used in the evaluation of
thyroid nodule and rates proved to be high. A stimulation test was performed, using
calcium as
secretagogue, and
calcitonin hyper-stimulation was confirmed, but anatomopathologic examination did not evidence medullar
neoplasia. Anatomopathologic diagnosis detected
Hashimoto thyroiditis in one case and adenomatous
goiter plus an occult
papillary thyroid carcinoma in the other one. Recommendation for routine use of serum
calcitonin in the initial diagnostic evaluation of a
thyroid nodule, followed by a confirming stimulation test if basal serum
calcitonin is showed to be high, is the most currently recommended approach, but questions concerning cost-benefit and possibility of diagnosis error make the validity of this recommendation discussible.