Thyroxine [HSA]

Context: Although a significant relationship has been reported between air pollution and thyroid function in limited samples or regions, few studies have addressed this association in the general population. Objective: Using a nationwide sample of Korean adults, we investigated the association between exposure to air pollution and thyroid function, and whether this association differed between subgroups stratified according to age or body mass index (BMI). Methods: We included 4704 adults in the final analysis and used each person's annual average exposure to 4 air pollutants, namely, particulate matter with an aerodynamic diameter less than or equal to 10 mu m (PM10), nitrogen dioxide (NO2), sulfur dioxide, and carbon monoxide (CO). We measured serum thyrotropin (TSH) and free thyroxine (FT4) concentrations as indicators of thyroid function according to age and BMI. Results: The annual average exposure to NO2 and CO was significantly associated with an elevated TSH and reduced FT4 concentration after adjusting for possible confounding factors (all P < .05). In men, in addition to these 2 pollutants, PM10 exposure was positively associated with TSH level (P = .03). Age-stratified analysis showed stronger effects of NO2 and CO exposure in older than in younger adults. Exposure to these air pollutants was related to serum TSH and FT4 concentrations in people with overweight or obesity but not in those of normal weight. Conclusions: This study provides the first evidence that air pollution exposure is linked to thyroid function in the general population and that this association may be stronger in older or overweight or obese adults.

Background. Hypothyroidism is a highly prevalent and multifactorial disorder and has been implicated in the causation of dyslipidemia, dermatological diseases, atherosclerosis, and myocardial dysfunction, as well as endothelial dysfunction. The relationship between subclinical hypothyroidism and type 2 diabetes mellitus is not well established. In the present study, we attempt to find out the prevalence of subclinical hypothyroidism in type 2 diabetes mellitus and its association with glycemic control.Materials and Methods. This was an observational study in which 205 consecutive patients of T2DM visiting the outpatient department of medicine were recruited. Serum TSH, free thyroxine, free triiodothyronine, and lipid profile, as well as HbA1c assays, were done in the study participants, and they were categorized into three groups by HbA1c: <7%, 7-9%, and >9%.Results. There is a high prevalence of subclinical hypothyroidism in type 2 DM patients. Mean HbA1c in diabetics without SCH was 7.89%, whereas it was 8.33% in diabetics with SCH. This difference was statistically not significant. TSH was not found to be significantly associated with HbA1c.Conclusion. High prevalence of SCH in T2DM patients suggests that there is a need for regular follow-up to check the progression of SCH to overt hypothyroidism. High serum TSH is not a predictor of poor glycemic control.