Endocrine Abstracts

Background: Studies on thyroid hormones in obese adult patients are contradictory. Moreover, little is known about the effect of weight loss on thyroid functions. Thus, we aimed to investigate thyroid hormone status, and possible effect of weight loss on thyroid hormones in obese patients.

Methods: We study population consisted of 39 (35 female, 4 male) euthyroid obese patients with mean age 42.76±10.52 years. Of these 19 patients were morbid obese. Weight, BMI, waist circumference, thyroid functions were evaluated initially and after 3 month of orlistat (120 mgr, three times a day) and sibutramine(15 mgr, once a day) treatment period.

Results: Morbid obese patients had higher total T4 (9.40±1.7 vs. 8.7±1.9 ug/dl, respectively, P=0.048) and total T3 (162.06±36.9 vs. 151.49±36.4 ng/dl, respectively P=0.039) levels compared to those of obese; however TSH, free T3 and free T4 levels were similar in obese and morbid obese patients. There were no statistically significant difference between the orlistat and sibutramine groups with regard to age, sex and BMI. Weight loss with orlistat therapy (mean 6.59±4.62 kg/3 month) decreased free T3 levels (4.17±2.13 vs. 3.08±0.63 pg/dl, respectively, P=0.042). However, TSH, total T4, total T3 and free t4 were not significantly changed. Weight loss with sibutramine therapy (mean 8.59±4.92 kg/3 month) were not significantly changed TSH and any other thyroid hormone levels.

In correlation analysis, weight was positively correlated with total T3 (r=0.280; P=0.043) levels. BMI was positively correlated with total T3(r=0.318; P=0.022) and total T4(r=0.281; P=0.044). In addition, waist circumference was positively correlated with total T3(r=0.434; P=0.001) levels.

Conclusion: Degree of obesity may effect thyroid hormone status. The effects of sibutramine and orlistat on thyroid hormone status may be different beyond lowering body weight.