Thyroid Volume Stabilization and Nodule Progression After Bariatric Surgery: Insights from a Retrospective Study

Studies investigating the effects of bariatric surgery (BS) on the thyroid are quite limited. The aim of our study is to evaluate changes in thyroid function and thyroid morphology in patients after BS.

This retrospective study included a total of 122 patients. Of these, 33 underwent BS and 89 did not undergo surgery. In the BS group, preoperative and postoperative one-year thyroid function tests, changes in ultrasonographic findings, and contributing factors were evaluated, while in the control group, changes from baseline to one-year were examined.

There were no baseline differences between the groups in terms of demographic, laboratory and ultrasonographic data. In the BS group, TSH and fT3 levels significantly decreased (p = 0.005 and 0.002), with the decrease in TSH being independently associated with an increase in HDL-cholesterol (β = -0.018, p = 0.040). No significant changes in thyroid function were observed in the control group. Thyroid volume increased significantly in the control group but not in the BS group (p = 0.034 vs. 0.270). A significant increase in the largest nodule diameter was observed after BS (β = 2.656, p = 0.033), independent of changes in BMI and thyroid function. No significant change in nodule diameter was observed in the control group. However nodule count increased in both groups, no difference was found between them (p = 0.745).

We observed that BS was associated with a reduction in TSH and fT3 levels, progression of thyroid nodule diameter, and prevention of thyroid volume increase. To the best of our knowledge, this is the first study to evaluate nodule size changes post-BS versus controls.