Measuring calcitonin levels in the washout fluid of fine-needle aspiration (FNA-CT) is significantly more sensitive than cytology after FNA in detecting medullary thyroid carcinoma (MTC), according to a new study published in Endocrine.  

“Accordingly, FNA-CT represents the standard method to use in patients with suspicious MTC lesions, combined with cytology,” first author Pierpaolo Trimboli, MD, and the coauthors of the study concluded.

Cytology after FNA is not sensitive in detecting MTC, so FNA-CT has been used as an alternative method. However, no evidence-based studies have systematically compared the 2 approaches.

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In the present study, a team of researchers led by Maurilio Deandrea, MD, PhD, of UO Endocrinologia, Diabetologia e Malattie del metabolismo, AO Ordine Mauriziano Torino in Italy, systematically reviewed the literature and collected data to conduct a head-to-head comparison meta-analysis between cytology after FNA and FNA-CT in detecting MTC lesions.

They included 6 studies in their analysis. They found that the sensitivity of cytology after FNA varied between 20% and 86%. It had a pooled value of 54% and significant heterogeneity. In comparison, the sensitivity of FNA-CT was higher than 95% in almost every study. The pooled value was 98% without heterogeneity.

The researchers concluded that their analysis confirmed that cytology after FNA can only detect around half of histologically proven MTC cases and that FNA-CT is significantly more sensitive.

The timing of the detection of MTC is very important in terms of patient outcomes because a delay in diagnosis, and therefore treatment, is associated with a poor prognosis.

Calcitonin is the most sensitive circulating marker of MTC. However, several factors can interfere with its levels, and its routine use as a diagnostic marker in all patients with nodular thyroid disease is not generally accepted.


Trimboli P, Giannelli J, Marques B, Piccardo A, Crescenzi A, Deandrea M. Head-to-head comparison of FNA cytology vs. calcitonin measurement in FNA washout fluids (FNA-CT) to diagnose medullary thyroid carcinoma. A systematic review and meta-analysis. Endocrine. Published online October 4, 2021. doi:10.1007/s12020-021-02892-x