O.A. Taylor3, M. Mulder1, C. Dougherty1, A. Kotwal2, A. Patel2, A. Fingeret1 1University Of Nebraska College Of Medicine, Department Of Surgery, Omaha, NE, USA 2University Of Nebraska College Of Medicine, Department Of Medicine, Omaha, NE, USA 3University Of Nebraska College Of Medicine, Omaha, NE, USA
Introduction:
A common concern among thyroid surgical candidates is that they will experience significant weight gain post-operatively. The relationship between thyroid function and weight is well established, though the impact of thyroid surgery on weight remains unclear. The present study examined weight change following thyroid surgery.
Methods:
We performed a retrospective cohort study of adult patients in an institutional database from 2003-2023 including those who underwent thyroid surgery and control patients who did not have surgically treated thyroid disease. All patients included had weight and body mass index (BMI) recorded at two time points greater than six months apart, surgical patients had weight and BMI recorded at the time of their operation. For the surgery group, only the index operation was included. Exclusion criteria were reoperative cases for the surgery group. Univariate analysis was performed with nonparametric statistics including Mann Whitney U and Kruskal Wallis testing with significance of p < 0.05. Our primary outcome was the association between thyroid surgery and weight change. Secondary outcomes were association of weight change with malignant histology, extent of surgery with total thyroidectomy (TT) versus thyroid lobectomy (TL), or patient sex. We evaluated BMI at time of surgery for association with weight change (BMI categories: <25kg/m2, 25-30, 30-35, 35-40, 40-50, >50). Median follow up time was 9.27 years (4.8-13.3) and did not differ between the surgery and control groups.
Results:
A total of 1,074 adult patients (865 female) who underwent thyroid surgery and 983 controls (783 female) met inclusion criteria. Overall, there was no difference in weight change between the surgery (median 1.01kg, IQR -4.1–6.7) and control (median 0.7kg, -5.1-6.9) groups (p=0.31). For the surgery group weight change was similar by benign (0.8kg, -4.3-5.9) and malignant (1.13kg, -4.1-7.0) pathology (p=0.54) and similar for TT (1.25kg, -4.2-7.0) and TL (0.57kg, -4.0-5.6) groups (p =0.43). Female sex was associated with weight gain (1.17kg, -4.3-7.21) compared with male sex (-0.1kg, -6.7-5) overall (p=0.0005), and for surgery patients: female 1.14kg (-3.7 – 7.2) compared with male 0kg (-6.39 – 4.65), p=0.0012. Weight change was significantly associated with BMI category at time of surgery for female patients (p=0.0001), but not for male patients (p=0.22) (Figure).
Conclusion:
Our study found no overall association between thyroid surgery and weight change including for those with cancer or by extent of surgery. Female sex was associated with weight gain for all groups. Weight gain was inversely associated with BMI category at the time of surgery for female patients.