Association of serum TSH with high body mass differs between smokers and never-smokers.
BACKGROUND
Recent studies have suggested that the association of low thyroid function with high body mass is restricted to nonsmokers.


OBJECTIVE
The aim was to study the association of thyroid function with body mass separately for smokers and never-smokers.


METHODS
We conducted a cross-sectional, population-based study.


METHODS
We studied 27,097 individuals older than 40 yr of age who were without previously known thyroid disease.


METHODS
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).


RESULTS
TSH within the reference range was positively associated with BMI (P for trend < or = 0.001 in all groups) and with the prevalence of obesity (P for trend < 0.005 in all groups). Among women, the association did not differ between current smokers and never-smokers, but in men the association was stronger for current smokers. Hypothyroid function was associated with higher BMI and higher prevalence of obesity in women (subclinical and overt hypothyroidism) and men (subclinical hypothyroidism), both in current smokers and in never-smokers.


CONCLUSIONS
The association of low thyroid function with high body mass was as least as strong in current smokers as in never-smokers, and our results clearly show that the association is not limited to nonsmokers, as previously suggested.
Department of Public Health, Faculty of Medicine, Norwegian University of Science and Technology, N-7489 Trondheim, Norway. bjorn.o.asvold@ntnu.no
Bjørn Olav
BO
Asvold
Trine
T
Bjøro
Lars J
LJ
Vatten
D015992:Body Mass Index; D001835:Body Weight / Q000502:physiology*; D005260:Female; D006801:Humans; D007037:Hypothyroidism / Q000097:blood / Q000503:physiopathology; D008297:Male; D009664:Norway / Q000453:epidemiology; D009765:Obesity / Q000097:blood; D012907:Smoking / Q000097:blood* / Q000453:epidemiology; D013960:Thyroid Function Tests; D013972:Thyrotropin / Q000097:blood*; D013974:Thyroxine / Q000097:blood; D014284:Triiodothyronine / Q000097:blood; D055815:Young Adult
D014284:Triiodothyronine; D013972:Thyrotropin; D013974:Thyroxine