Epidemiologic Study Of The Effect Of Smoking Cigarette On Thyroid Gland

ObjectiveTo investigate the effect of smoking cigarette on the thyriod gland volume, thyroid function and thyroid autoantibodies in the areas with different iodine intakes.MethodsA cross-sectional epidemiologic study in Panshan (mild iodine-deficient area), Zhangwu (more than iodine-sufficient area )and Huanghua (iodine-excessive area) was conducted in 3761 subjects in 1999 .Of them 884,1270,and 864 participants were investigated in 2004 with 80.2% of follow-up rate. The questionnaires were filled in by all the subjects . Tests for thyroid function, thyroid autoantibodies, urinary iodine concentration, as well as thyroid B ultrasound were also performed .ResultsThe prevalence of goiter was higher in smokers than non-smokers (15.1% vs 11.5%,p<0.05). The average thyroid volume was 14.92ml in the smoker group and 13.18ml in non-smoker group (p<0.05).The phenomenon was more obvious in Panshan and Huanghua areas. The Logistic analysis showed that smoking cigarette, iodine deficiency, iodine sufficiency, age, and serum thyroid autoantibody level were the independent risk factors of increasing the goiter prevalence. There was no difference between serum TSHlevel in smokers and non-smokers(1.87mu/L vs 2.04mu/L,p>0.05).The average serum Tg level was 18.57ng/ml in the smoking group and 17.01ng/ml in the non-smoking group, which indicated the smoking did not affect the serum Tg level. The significant difference was found in positive rate of TPOAb with 10.8% in smokers and 9.0% in non-smokers, which was especially obvious in the iodine-excessive area. But the difference of TgAb positive rate was not remarkable between the smoking and the non-smoking groups (6.6% vs 8.1%, p>0.05).The Logistic analysis showed that age ,sex, smoking cigarette, TgAb were the independent risk factors of increasing TPOAb positive rate(TPOAb l00IU/ml).The more heavier the smoking cigarette, the higher the TPOAb positive rate. In the prospective observation in the subjects with high concentration of TPOAb and TgAb in the above three areas it was found that the incidence of positive TPOAb( 100IU/ml) was 53.8% in the subjects that non-smokers became smokers and 25.4% in that smoking did not change. The Logistic analysis indicated that the shifting from not smoking to smoking was independent risk factor of increasing high incidence of positive TPOAb. The change of smoking had no effect on the disappearance of positive TPOAb( 100IU/ml) and the change of TgAb. In the group with abnormal serum TSH level, there was no difference between thyroid gland volume, function and TgAb in smokers and non-smokers. In the group with elevated serum TSH level(TSH>4.8mU/L), however, the positive rate of TPOAb( 100IU/ml) was increased in smokers. The Cox model showed that smoking cigarette and serum TgAb level were the risk factors of increasing the positive rate of TPOAb in the group with elevated serum TSH level.ConclusionSmoking was a risk factor of increasing prevalence of thyroid goiter. The average thyroid gland volume was higher in smokers than non-smokers. It was more obvious in the mild iodine-deficient area and iodine-excessive area. There was no difference between serum TSH or Tg level in smokers and...