Endocrine Abstracts

Background: Calcitonin is a hormone secreted by thyroid C cells, and is considered an excellent marker for medullary thyroid carcinoma (MTC). However, the use of calcitonin to screen patients with nodular thyroid disease (NTD) remains controversial.

Objective: Defining the frequency of hypercalcitoninemia among NTD patients followed at a tertiary referral hospital.

Methods: Retrospective analysis of basal calcitonin measurements and corresponding patients’ records between January 2011-December 2015. The method used was immunochemiluminescent assay. Hypercalcitoninemia was defined as >10 pg/ml.

Results: In five years, there was a total of 6551 calcitonin measurements requested, by different physicians from different services, to 5149 patients: median age 57 years, 80.6% female. Calcitonin measurements were divided into 3 groups according to their levels: GI ≤10 pg/ml; GII 10–100 pg/ml; GIII ≥100 pg/ml. Excluding patients with no clinical information, there were 3097, with the following distribution: GI 2913, GII 158, GIII 26. Among these, calcitonin was requested in NTD context to 1504 patients: 69 patients had hypercalcitoninemia (GII and GIII). Of these, 21 underwent surgery (GI 12, GIII 9); a histological diagnosis of MTC was established in 12 (GII 3/25%, GIII 9/100%). Surgery was decided based, solely, on calcitonin levels in 7 cases, since only 5 had a positive cytology.

Conclusions: NTD was the reason for calcitonin measurement in less than 50% of total measurements. Hypercalcitoninemia was found in 4.6% of NTD patients. Calcitonin levels ≥100 were associated to a greater CMT risk, comparative to values between 10 and 100 and reinforcing results from other groups. A cost-effective approach includes avoid unnecessary requests, adequate interpretation of results as well as appropriate selection of patients to surgery.