Background: Obesity is an established risk factor for cardiovascular disease and a cause for early mortality but there is a metabolically healthy obese (MHO) subtype and interests in its characteristics are increasing. Thyroid hormone is one of the important hormones engaged in energy metabolism but its association with obesity and metabolic complication is not well known. This study was conducted to examine whether thyroid hormones including thyrotropin (TSH), triiodothyronine (T3) and free thyroxine (fT4) have any relationships with the components of metabolic syndrome including waist circumference, blood pressure, serum triglyceride (TG), high density lipoprotein (HDL) and fasting glucose in obese subjects within normal range of thyroid function test.
Methods: A total of 774 men and 298 women, aged 21~88 years, with body mass index above 25 kg/m2 and TSH level between 0.15 and 5.0 mIU/L were studied. Self-reported questionnaire about medical history and routine screening tests were performed. Waist circumference, blood pressure, serum triglyceride, high density lipoprotein, fasting glucose and serum TSH, T3 and fT4 were measured.
Results: In obese males, serum TSH and T3 were positively associated with systolic and diastolic blood pressure and serum TG level. In obese females, TSH was positively related with waist circumference and TG while T3 was positively related with waist circumference, systolic and diastolic blood pressure and TG..
Conclusion: Thyroid hormones were associated with the components of metabolic syndrome. Metabolically healthy obese males with none or one component of metabolic syndrome risk factor showed lower TSH and lower T3 level. Metabolically healthy females had a relatively lower T3 level compared to the metabolically unhealthy obese subjects with more than two components of metabolic syndrome.
|