Effect of Laparoscopic Roux-en-Y Gastric Bypass Surgery on Thyroid Hormone Levels in Chinese Patients, Could It Be a Risk for Thyroid Nodules?

OBJECTIVES

The study aimed to evaluate the changes in thyroid function and the risk of thyroid tumors after Roux-en-Y gastric bypass (RYGB) surgery.

MATERIALS AND METHODS

This was a retrospective study of 117 patients with type 2 diabetes (T2D) and obesity who underwent laparoscopic RYGB (LRYGB) and were followed up for 36 months. Thyroids were examined with ultrasonography. Binary logistic regression analysis was used for predictors of thyroid tumors, and receiver operating characteristic curve determined cutoff points.

RESULTS

Sixty-two patients (53.0%) were female. The mean age was 47.3 ± 11.8 years, and the mean follow-up duration was 36.4 ± 5.2 months. Fifty-one patients (43.6%) were diagnosed with thyroid nodules (TN) by ultrasonography before surgery. Overall, free triiodothyronine (FT3) and free thyroxine (FT4) levels decreased after LRYGB, while thyroid-stimulating hormone (TSH) levels remained stable, and all were within normal limits. Reduction in A1C was correlate with change in FT3 (P = 0.043) and FT4 (P = 0.001). Forty-one patients (35.0%) had TN or had progressive TN after LRYGB, while two patients were diagnosed with malignant tumors at 12 months. The preoperative body fat ratio and FT3/FT4 ratio were clinical predictors of TN progression.

CONCLUSIONS

LRYGB effectively treated obese patients with T2D. Serum FT3 and FT4 levels decreased to within normal limits after LRYGB. Changes in TSH were not correlated with weight loss. Patients after LRYGB had a potential risk of thyroid nodule progression, preoperative high body fat ratios, or low FT3/FT4 ratios that had higher risks of TN.