Total weight loss induces the alteration in thyroid function after bariatric surgery

Area of Science:

• Endocrinology
• Bariatric Surgery
• Metabolic Health

Background:

• Bariatric surgery is a recognized method for significant weight reduction.
• Its impact on thyroid function, particularly thyroid-stimulating hormone (TSH) and thyroid hormones, remains a subject of ongoing research and debate.
• The precise relationship between the degree of weight loss and changes in thyroid parameters post-surgery requires further elucidation.

Purpose of the Study:

• To investigate the alterations in thyroid hormones and TSH following bariatric surgery.
• To determine the correlation between the percentage of total weight loss (%TWL) and the change in TSH (ΔTSH) one year after surgery.
• To assess whether postoperative weight loss is an independent predictor of ΔTSH.

Main Methods:

• Retrospective analysis of euthyroid patients with obesity undergoing sleeve gastrectomy or Roux-en-Y gastric bypass (2017-2022).
• Measurement of TSH, free thyroxine (FT4), free triiodothyronine (FT3), total thyroxine (TT4), and total triiodothyronine (TT3) levels one year post-surgery.
• Application of Pearson correlation and multivariable linear regression to analyze the relationship between %TWL and ΔTSH.

Main Results:

• A total of 256 patients were analyzed, achieving a mean %TWL of 28.29% after one year.
• Significant decreases were observed in TSH, FT3, FT4, TT3, and TT4 levels one year post-bariatric surgery (P < 0.001 for all).
• Pearson correlation revealed a significant positive correlation between %TWL and ΔTSH (r=0.184, P=0.003). Multivariable regression confirmed %TWL as an independent predictor of ΔTSH (β=0.180, P=0.008).

Conclusions:

• Bariatric surgery leads to significant reductions in TSH and thyroid hormone levels one year post-procedure.
• Postoperative weight loss is an independent factor influencing the decline in TSH.
• Increased weight loss is associated with a greater reduction in TSH levels.