Effect of sleeve gastrectomy on thyroid hormone levels

Weight loss in morbidly obese patients is associated with changes in thyroid function. Studies have demonstrated equivalent changes following bariatric surgery. Changes in thyroid function were reported following laparoscopic Roux-en-Y gastric bypass (LRYGB), biliopancreatic diversion (BPD), and laparoscopic adjustable gastric banding (LAGB). No data exists on changes in thyroid function following laparoscopic sleeve gastrectomy (LSG). The aim of the current study is to evaluate changes in thyroid function following LSG in patients with normal thyroid function.

Data were retrieved from a prospectively collected database of patients who underwent LSG for morbid obesity. Euthyroid patients were evaluated for changes in TSH and free thyroxine (FT4), 6-12 months after surgery. Correlation between changes in thyroid hormone levels, excess weight loss (EWL), and baseline TSH were evaluated.

Thirty-eight patients were included in the study. Mean BMI decreased from 42.4 to 32.5 kg/m(2) (P < 0.0001). Mean TSH levels decreased from 2.45 ± 0.17 mU/L at baseline to 1.82 ± 0.18 mU/L (P < 0.0001), whereas mean FT4 levels remained the same after surgery (13.27 ± 0.45 pmol/L compared to 12.96 ± 0.42 pmol/L, P = NS). TSH decrease was directly related to baseline TSH but did not correlate with EWL.

This is the first study to evaluate changes in thyroid hormone levels following LSG for morbid obesity. TSH decrease and steady levels of FT4 are expected following LSG. These findings are comparable to reported changes following LRYGB. TSH decrease was not associated with EWL. Further studies are required to elucidate the exact mechanism of this effect.