Impact of Obesity on Serum Levels of Thyroid Hormones among Euthyroid Saudi Adults

AIM OF STUDY: To assess serum thyroid hormones levels among Saudi adults and to correlate participants' serum levels with their grades of body mass index (BMI). METHODOLOGY: A total of 278 adult subjects were recruited. Participants were categorized according to their BMI grades into normal weight (BMI < 25 kg/m(2)), overweight (BMI 25–29.9 kg/m(2)), or obese (BMI ≥ 30 kg/m(2)). Serum thyroid hormones levels were assessed at the central laboratory of Aseer Central Hospital, Abha City, by chemiluminescence immunoassay. RESULTS: More than three-fourths of participants were either overweight (31.3%) or obese (44.6%). Mean TSH serum levels showed a significantly increasing trend with increasing BMI (p < 0.001). A negative trend was observed regarding participants' mean serum levels of fT4 with their BMI, but there were no significant differences in mean serum fT4 levels according to BMI. Moreover, no significant differences were observed in serum fT3 levels according to BMI. CONCLUSIONS: Mean TSH serum levels increase with BMI increase. Further largescale multicentric and longitudinal studies are necessary to prove the association between serum levels of thyroid hormones and BMI of euthyroid adults.