Introduction: In obese patients, the incidences of several thyroid disorders have increased
in comparison to the general population. This study is aimed to investigate the effect of laparoscopic
sleeve gastrectomy (LSG) on thyroid function tests in obese patients.
Methods: The patient files of 186 individuals who underwent laparoscopic sleeve gastrectomy surgery
were examined retrospectively. Forty-nine females and 29 males comprising a total of 78 patients were
included in the study. The routine physical examination findings and laboratory parameters recorded
preoperatively were compared with their counterparts obtained in the postoperative sixth month.
Results: The mean preoperative body mass index (BMI) levels of the patients in the study was calculated
as 46.91 kg/m2, whereas the mean BMI in the postoperative sixth month was 30.35 kg/m2
(p<0.001). Prior to the sleeve gastrectomy, the mean thyroid stimulating hormone (TSH) level of the
patients was 2.53 ±2.06 µIU/mL; however, a significant reduction was observed in the mean TSH level
during the postoperative sixth month, which was calculated as 1.77 ±1.12 µIU/mL (p=0.015). The
mean free T4 level was 1.18±0.1 ng/dL in the preoperative period, but this increased to 1.22 ±0.24
ng/dL postoperatively, an insignificant change. The decrease in the TSH levels after the LSG was determined
not to be correlated with the decrease in body weight.
Conclusion: The results of our study demonstrate that the levels of TSH decreased significantly in
patients who underwent LSG and that the decrease was independent of the changes in BMI.