Recent studies have suggested that the association of low thyroid function with high body mass is restricted to nonsmokers.
The aim was to study the association of thyroid function with body mass separately for smokers and never-smokers.
We conducted a cross-sectional, population-based study.
We studied 27,097 individuals older than 40 yr of age who were without previously known thyroid disease.
We measured mean body mass index (BMI) and odds ratio for obesity (BMI > or = 30.0 kg/m(2)) according to categories of thyroid function, in women and men, and separately for current smokers and never-smokers. We also studied the association with BMI within the reference range of TSH (0.50-3.5 mU/liter).
TSH within the reference range was positively associated with BMI (P for trend