Background: The effect of weight-reducing surgeries on thyroid function in morbid obese patients was evaluated by
several studies. However, because of the variability of the techniques and the degrees of hypothyroidism, their results
were inconsistent. So, our aim in this study was to evaluate the effect of laparoscopic sleeve gastrectomy (LSG) on thyroid
function in obese patients with subclinical hypothyroidism (SH) seeking weight reduction as it is considered the most
common weight-reducing surgery performed and compare its results with malabsorptive procedures.
Patients and Methods: This is a retrospective study evaluating all obese patients that underwent different weightreducing
procedures with a preoperative diagnosis of SH from June 2020 to June 2023, evaluating the thyroid function in
obese patients after surgery.
Results: One hundred thirty-four (9.3%) out of the 1450 morbidly obese patients that underwent LSG (82/813), Rouxen-
Y gastric bypass (RYGB) (41/397) and mini-gastric bypass (MGB) (11/240) during the study period were found to
have SH during the preoperative investigations. Hypothyroidism improved in 50 (60.9%) patients and completely resolved
in 20 (24.3%) patients, while 11 (13.4%) patients experienced no improvement, and one (1.4%) patient developed overt
hypothyroidism following LSG after 1 year of follow up. Hypothyroidism improved in 16 (39%) patients and completely
resolved in 23 (56%) patients, while two (5%) patients experienced no improvement following RYGB after 1 year of
follow-up. Hypothyroidism improved in four (36.3%) patients and completely resolved in six (54.5%) patients, while one
(9.2%) patient experienced no improvement following MGB after 1 year of follow-up. The mean excess weight loss after
1 year of surgery was 43.7% after LSG, 49.2% after RYGB, and 50.1% after MGB.
Conclusion: Obesity itself has a significant impact on thyroid function, and different bariatric surgeries produce a
significant improvement of SH.