Association of Thyroid Surgery With Body Mass Index: a 10-Year Cohort Study.

INTRODUCTION

A common concern among thyroid surgical candidates is significant weight gain postoperatively. The association of thyroid surgery with weight remains unclear.

METHODS

We performed a retrospective cohort study of adult patients with thyroid nodule disease and body mass index (BMI) records in an institutional database from 2003 to 2023 who did or did not have thyroid surgery. We assessed an association between surgery and change in BMI. The secondary outcomes were an association of change in BMI with clinicopathologic variables. Parametric analyses were performed on the propensity-matched cohort.

RESULTS

A total of 2346 patients were included: 1173 surgical patients and 1173 controls. Overall, there were no differences in BMI change in 10 y of follow-up. Surgical patients had a mean increase of 1.08 kg/m2 (95% confidence interval: 0.63-1.54) versus 0.70 kg/m2 (95% confidence interval: 0.31-1.09) in the nonsurgical group (P = 0.21). Both surgical patients and controls experienced modest increases in BMI over 10 y, which align with expected age-related changes. At 10 y, there were no significant associated differences in BMI by sex (P = 0.19), extent of surgery (P = 0.22), thyroid-stimulating hormone level (P = 0.64), or pathology (P = 0.54). Weight change was not associated with surgery other than underweight BMI at the time of surgery.

CONCLUSIONS

Our study found no association between thyroid surgery and change in BMI. Over 10 y, time was associated with an increase in BMI within each group but was comparable between groups. Our results provide reassurance that thyroid surgery is unlikely to be associated with long-term BMI changes.