Effect of weight loss after gastric bypass surgery on thyroid function in euthyroid people with morbid obesity

Abstract

Obesity is positively associated with serum thyrotropin (TSH) concentrations at the high end of the normal range. The relationship between weight loss and thyroid function is less clear and studies to date have yielded inconsistent results. Our aim was to describe changes in thyroid function in obese people in relation to durable and significant weight loss after Roux-en-Y gastric bypass (RYGB) surgery. We recorded percentage of excess weight loss (% EWL), serum TSH and free thyroxine (fT4) before and median 4.5, 15 and 24 months after RYGB in 55 euthyroid patients with morbid obesity ranging in age from 18 to 64 years in a retrospective cohort analysis in a university hospital in Greater Manchester. Mean ± standard error preoperative weight was 135.13 ± 4.23 kg and BMI 48.08 ± 1.58 kg m(-2) . Patients attained nadir %EWL of 68% by median 15 months after RYGB. TSH was 2.00 ± 0.14 mU L(-1) at baseline and 2.02 ± 0.22 mU L(-1) at 24 months after RYGB (non-significant). Baseline fT4 was 13.46 ± 0.28 pmol L(-1) , and increased significantly to 15.14 ± 0.55 pmol L(-1) at 24 months (P < 0.004). In conclusion, we report that weight loss after RYGB was accompanied by significant increase in serum fT4 but no change in TSH concentrations. Further study to elucidate the effect of significant weight loss on the thyroid axis is required.

Effect of Weight Loss after Bariatric Surgery on Thyroid-Stimulating Hormone Levels in Patients with Morbid Obesity and Normal Thyroid Function

“…Most [12][13][14][15][16], but not all [17][18][19], studies evaluating the variation of TSH after bariatric surgery have also shown a decrease of TSH after the procedure. Moulin de Moraes et al [13] reported that in 54 euthyroid patients submitted to RYGB there was a significant decrease in TSH that was not correlated to percent change in BMI and a significant decrease in FT3 but not in FT4.…”

“…On the other hand, the impact of bariatric surgery on FT4 levels is more controversial with different studies reporting decreasing [22], A: Univariate analysis of TSH variation at 12 months after bariatric surgery. B: Multivariate analysis of TSH variation at 12 months after bariatric surgery BMI body mass index, TSH thyroid-stimulating hormone, FT4 free thyroxine, FT3 free triiodothyronine stable [12][13][14]18], or increasing [17,19] levels after bariatric surgery. We must highlight that this is the largest study to date evaluating the effect of bariatric surgery on TSH variation in euthyroid patients with morbid obesity and that our evaluation was not restricted to a type of surgery, including three of the most common surgeries for treatment of morbid obesity.…”

“…The mechanism and the clinical implications of this alteration remains uncertain. Furthermore, the effect of bariatric surgery on postoperative thyroid function remains incompletely understood with previous studies showing contradictory results regarding the variation of TSH after bariatric surgery and the relation of TSH variation with postoperative weight loss [12][13][14][15][16][17][18][19]. Therefore, our aim was to evaluate the effect of weight loss after bariatric surgery on TSH variation in patients with morbid obesity and normal thyroid function.…”

Decreased Leptin Is Associated with Alterations in Thyroid-Stimulating Hormone Levels after Roux-en-Y Gastric Bypass Surgery in Obese Euthyroid Patients with Type 2 Diabetes

“…Comparable results were described by Chikunguwo et al [16]in a 12-month follow-up study which enrolled 86 euthyroid obese patients after RYGB or adjustable gastric banding surgery. On the contrary, MacCuish et al [17]reported that weight loss after RYGB was accompanied by a significant increase in serum FT 4 but no change in TSH in 55 euthyroid individuals with morbid obesity. Vettor et al [18]observed a significant decline in both FT 3 and FT 4 , while TSH remained unchanged in an 18-month follow-up study which enrolled 10 morbidly obese subjects receiving biliopancreatic diversion surgery.…”

Effect of Laparoscopic Sleeve Gastrectomy on Clinical Hypothyroidism in Morbidly Obese Patients

“…Improved thyroid status has been reported among obese patients following other bariatric surgical procedures [4][5][6][7][8][9][10][11][12], while few studies have been published on the effect of LSG on thyroid status [13][14][15].…”