Relação entre índice de massa corporal e tireotrofina sérica em mulheres eutiróideas residentes no município do Rio de Janeiro: diferenças segundo tabagismo, raça e menopausa

Abstract

Although, overt thyroid dysfunction is associated with weight changes, it is not known whether minor changes in thyroid function within normal serum thyrotropin (TSH) concentration could affect body mass index (BMI). The association between serum TSH and BMI in euthyroid subjects has been focus of recent and controversial studies. A possible explanation for these controversial findings could be the differences on this association between population subgroups. The aim of this study was to investigate the association between BMI and TSH in women with normal thyroid function and to evaluate a potential effect modification on the association between BMI and TSH by smoking, race, and menopause status. A population-based study was carried out in the city of Rio de Janeiro, Brazil, in 2004-2005. Sample selection was based on a three-stage cluster design. In the first stage, 100 primary sample units (PSU) were selected. In the second stage, 15 households were select from each PSU and in the third stage one woman was selected from each household. Of a sample of 1500 women aged 35 years or older, 1298 agree to participate. For the present study, a final sample of 1084 women without thyroid disease was investigated. Overall, BMI was positively and significantly associated with serum TSH (β=0.90; p- value=0.02) and stronger association between BMI and serum TSH among premenopausal women (β=1.04; p-value=0.04), Black women (β=1.39; p-value=0.14) and smokers (β=1.77; p-value=0.04) was found. In conclusion, TSH appears to modulate body weight among women even in the normal range. Smoking and race are strong effect modifiers of the association between TSH and BMI and future studies should take these effect modifiers into account.