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

Abstract

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/m2), overweight (BMI 25–29.9 kg/m2), or obese (BMI ≥ 30 kg/m2). 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.

Assessment of the simultaneous effect of hypothyroidism and thyroid autoimmunity with gestational diabetes on the incidence of type 2 diabetes

“…It has also been shown that hypothyroidism is more common among women with T2DM, compared to non-diabetic women [ 5 , 6 ], e.g., in a population-based prospective cohort study with 7.9-year follow up of 8452 individuals, hypothyroidism was reported as a risk factor for the incidence of T2DM, particularly among women with prediabetes [ 6 ]. Although the presence of T2DM and obesity was associated with the increased thyrotropin (TSH) concentration, the causal link between obesity and free triiodothyronine [FT3] and free thyroxin [FT4] is still under debate [ 7 , 8 ]. Therefore, it should be noted that the association of obesity and T2DM with hypothyroidism remains a gray area because subclinical hypothyroidism might well be secondary to obesity and T2DM [ 9 ].…”

The Association of Triiodothyronine-to-Thyroxine Ratio with Body Mass Index in Obese Nigerian Children and Adolescents

“…Solanki et al [ 32 ] and other authors [ 33 ] reported a significant positive association between participants’ BMI and their TSH mean serum levels, which was stated to suggest a state of possible sub-clinical hypothyroidism [ 15 ]. The association between TSH and BMI has been said to be under the influence of adipose tissue signals, and leptin has also been said to possibly have a significant effect on the central regulation of thyroid function through thyrotropin releasing hormone [ 34 ].…”

“…This may have been responsible for the significantly higher T3/T4 ratio observed in obese children, which may be an indication of thyroid function and thyroid hormone action on tissues. Triiodothyronine plays very important and critical roles that influence body weight, and such roles include temperature homeostasis, resting energy expenditure (REE) by modulating the interaction with adipose tissue to influence the adaptations of metabolism, spontaneous motor activity and thermogenesis [ 34 ]. The T3/T4 ratio can be elevated in hyperthyroidism and hypothyroidism due to higher efficiency of the thyroid gland in secreting T3 as well as increased 5′ deiodinase tissue activity [ 26 ].…”

Exposure to chemicals formed from natural processes is ubiquitous

“…Al-Musa correlated levels of serum thyroid hormones with body mass index (BMI) in 278 Saudi Arabian adults. 26 Slightly more than three-fourths of the study subjects were either overweight (31.3%) or obese (44.6%). Mean TSH serum levels showed a significant increase with increasing BMI, although T3 and T4 were not significantly related to BMI.…”