Endocrine Abstracts

Objective: Thyroid nodules are common in the population more than 90% are benign. Data about the long-term follow-up of benign nodular thyroid disease is limited. We aimed to clarify, clinical outcome, frequency and magnitude of volume changes in cytologically and/or sonographically benign nodules in long-term(> 5 years) follow-up and to determine the predictive features of nodule growth.

Methods: We retrospectively collected data of cytologically and/or sonographically benign 427 nodules from 221 euthyroid patients with 10 years of ultrasonographic follow-up(2004–2023) from the same tertiary center and sonographers. Thyroid autoantibody positivity, presence of more than 5 or confluent nodules that are difficult to interpret sonographically, were excluded. Nodule volume was calculated using the ellipsoid formula: a × b × c × 0.523.

Results: The volume change patterns of 427 nodules from 206 euthyroid patients (F/M=3/2), with the mean age 50.2±12.5 years] were analysed. Mean±s.d.TSH at the initial visit was 1.7±1.08 mIU/l. The median nodule volume was 0.47 (min-max=0.03-28.24)ml. When the nodules were examined according to their echogenic patterns, 47%(n =202) of the nodules were isoechoic, 25%(n =107) hypoechoic, 20%(n =85) mixed (iso-hypoechoic) and 8%(n =33) hyperechoic. Regarding nodule structure, 39%(n =165) of the nodules were solid and 61%(n =262 ) were mixed. Concerning the location(longitudinal axis), 13%(n =57) of the nodules were located in the upper third, 50% (n =215) in the middle and 37%(n =155) in the lower third. The percentage of nodule volume change at the 5th and 10th years were presented in Table 1. 70%(n =153) of the nodules that grew in the first 5 years continued to grow in 5-10 years. 46% of the stable nodules and 30% of the nodules which decreased in volume in the first five years grew between 5-10 years. The growth pattern in the second 5 years was significantly different from the first 5 years(McNemar-Bowker test, P = 0.02). A generalized mixed linear model revealed that age at diagnosis, male gender and initial nodule volume were significant predictors for the nodule volume change (OR=0.980 P = 0.037, OR:0.630 P = 0.040, OR:0.929 P = 0.019 respectively), where as echogenicity and location were not associated with nodule growth.

Conclusions: To our knowledge, this is the first 10-year retrospective follow-up of euthyroid benign nodular disease in the literature, we showed that young age, female gender and small initial nodule volume are predictive for increased nodule volume in long-term follow-up.