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Background@#Thyroid autoimmunity (TAI) is prevalent among women of reproductive age and associated with adverse pregnancy outcomes. This study aimed to investigate the association between iron nutritional status and the prevalence of TAI in women during the first trimester of pregnancy and in non-pregnant women of childbearing age.@*Methods@#Cross-sectional analysis of 7463 pregnant women during the first trimester of pregnancy and 2185 non-pregnant women of childbearing age nested within the sub-clinical hypothyroid in early pregnancy study, a prospective collection of pregnant and non-pregnant women’s data, was conducted in Liaoning province of China between 2012 and 2015. Serum thyrotropin, free thyroxine, thyroid peroxidase antibodies (TPOAbs), thyroglobulin antibodies (TgAbs), serum ferritin, and urinary iodine were measured. Iron deficiency (ID) was defined as serum ferritin <15 μg/L and iron overload (IO) was defined as ferritin >150 μg/L. TPOAb-positive was defined as >34 U/mL and TgAb-positive was defined as >115 U/mL. Multilevel logistic regression was conducted to examine the association between TAI and different iron nutritional status after adjusting for potential confounders.@*Results@#The prevalence of isolated TPOAb-positive was markedly higher in women with ID than those without ID, in both pregnant and non-pregnant women (6.28% vs. 3.23%, χ2 = 10.264, P = 0.002; 6.25% vs. 3.70%, χ2 = 3,791, P = 0.044; respectively). After adjusting for confounders and the cluster effect of hospitals, ID remained associated with TPOAb-positive in pregnant and non-pregnant women (odds ratio [OR]: 2.111, 95% confidence interval [CI]: 1.241–3.591, P = 0.006; and OR: 1.822, 95% CI: 1.011–3.282, P = 0.046, respectively).@*Conclusion@#ID was associated with a higher prevalence of isolated TPOAbs-positive, but not with isolated TgAb-positive, in both pregnant women during the first trimester of pregnancy and non-pregnant women of childbearing age, while IO was not associated with either isolated TPOAb-positive or isolated TgAb-positive.@*Clinical trial registration@#ChiCTR-TRC-13003805, http://www.chictr.org.cn/index.aspx.
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BACKGROUND@#Thyroid autoimmunity (TAI) is prevalent among women of reproductive age and associated with adverse pregnancy outcomes. This study aimed to investigate the association between iron nutritional status and the prevalence of TAI in women during the first trimester of pregnancy and in non-pregnant women of childbearing age.@*METHODS@#Cross-sectional analysis of 7463 pregnant women during the first trimester of pregnancy and 2185 non-pregnant women of childbearing age nested within the sub-clinical hypothyroid in early pregnancy study, a prospective collection of pregnant and non-pregnant women's data, was conducted in Liaoning province of China between 2012 and 2015. Serum thyrotropin, free thyroxine, thyroid peroxidase antibodies (TPOAbs), thyroglobulin antibodies (TgAbs), serum ferritin, and urinary iodine were measured. Iron deficiency (ID) was defined as serum ferritin 150 μg/L. TPOAb-positive was defined as >34 U/mL and TgAb-positive was defined as >115 U/mL. Multilevel logistic regression was conducted to examine the association between TAI and different iron nutritional status after adjusting for potential confounders.@*RESULTS@#The prevalence of isolated TPOAb-positive was markedly higher in women with ID than those without ID, in both pregnant and non-pregnant women (6.28% vs. 3.23%, χ = 10.264, P = 0.002; 6.25% vs. 3.70%, χ = 3,791, P = 0.044; respectively). After adjusting for confounders and the cluster effect of hospitals, ID remained associated with TPOAb-positive in pregnant and non-pregnant women (odds ratio [OR]: 2.111, 95% confidence interval [CI]: 1.241-3.591, P = 0.006; and OR: 1.822, 95% CI: 1.011-3.282, P = 0.046, respectively).@*CONCLUSION@#ID was associated with a higher prevalence of isolated TPOAbs-positive, but not with isolated TgAb-positive, in both pregnant women during the first trimester of pregnancy and non-pregnant women of childbearing age, while IO was not associated with either isolated TPOAb-positive or isolated TgAb-positive.@*CLINICAL TRIAL REGISTRATION@#ChiCTR-TRC-13003805, http://www.chictr.org.cn/index.aspx.
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<p><b>OBJECTIVE</b>To investigate the effect of cigarette smoking on thyroid gland volume, thyroid function and thyroid autoantibodies in the areas with different iodine intakes.</p><p><b>METHODS</b>A cross-sectional epidemiological study in Panshan (mild iodine-deficient area), Zhangwu (more than adequate iodine intake area) and Huanghua (iodine-excessive area) was conducted in 3761 subjects in 1999.80.2 % of them were followed up in 2004. Questionnaires, thyroid function, thyroid autoantibodies, urinary iodine concentration,and thyroid B ultrasound were performed.</p><p><b>RESULTS</b>The prevalence of goiter was higher in smokers than in non-smokers (15.1% vs. 11.5%, P< 0.05). The average thyroid volume was higher in smokers with phenomenon more obvious in Panshan and Huanghua areas. Data from logistic analysis showed that smoking cigarette was an independent risk factor of goiter. There was no difference in serum TSH and Tg level between smokers and non-smokers. The positive rate of TPOAb (>100 IU/ml) was higher in smokers than in non-smokers(10.8% vs. 9.0 % , P <0.05) and was especially obvious in Huanghua area. Smoking was a independent risk factor of increasing positive rate of TPOAb. During the prospective observation,it was found that the incidence of positive TPOAb(>,100 IU/ml) was 7.4% in the subjects that were from non-smokers turning to smokers and 2.9% in those whose smoking behavior did not change. Logistic analysis indicated that the shifting from non-smoking to smoking was independent risk factor for the increase on high incidence of positive TPOAb.</p><p><b>CONCLUSION</b>Smoking cigarette was a independent risk factor of goiter. Smoking was also a risk factor of increasing TPOAb positive rate. Shifting from not smoking to smoking was an independent risk factor of increasing high incidence of positive TPOAb.</p>
Subject(s)
Female , Humans , Male , Autoantibodies , Blood , Cross-Sectional Studies , Goiter , Blood , Epidemiology , Allergy and Immunology , Incidence , Smoking , Thyroid Function Tests , Thyroid Gland , Thyroid Hormones , BloodABSTRACT
Objective To investigate epidemiologieal characteristics of hypothyroidism and factors influencing its outcome in the areas with different iodine intakes.Methods An epidemiologic follow-up study of thyroid diseases was performed in Panshan (iodine deficient),Zhangwu [mild iodine deficiency before universal salt iodination (USI) and more than adequate iodine intakes after USI ] and Huanghua ( iodine excessive) in China.A total of 3 761 subjects were investigated in 1999,and 3 018 (80.2% ) of them were followed up in 2004.FT_4,FT_3,TSH,thyroid autoantibodies and urinary iodine concentration were determined and thyroid B ultrasound was performed in all participants.Results Five-year cumulative incidence of overt hypothyroidism was 0.23%,0.47% and 0.35% in Panshan,Zhangwu and Huanghua,respectively.Twenty patients with autoimmune- induced overt hypothyroidism did not comply with the physician's orders to take thyroxine.Thyroid function spontaneously turned to normal in 55% of them,turned to subclinical hypothyroidism in 20% and maintained overt hypothyroidism in 25%.Five-year cumulative incidence of subclinical hypothyroidism in Zhangwu (2.60%) and Huanghua (2.89%) were significantly higher than that in Panshan(0.23% ) (both P＜0.01 ).One hundred patients with subclinical hypothyroidism were followed up,and 5% of them developed overt hypothyroidism,66% turned to euthyroidism and 29% maintained subclinical hypothyroidism.Raised serum TSH (＞6 mU/L) in the original survey ( OR = 3.4),positive thyroid autoantibodies in the follow-up study ( OR = 5.3 ) and more than adequate iodine supplementation in the mild iodine-deficient population ( OR = 8.0) were risk factors influencing outcome of subclinical hypothyroidism.Conclusion More than adequate iodine supplementation among a population in the mildly iodine-deficient area may increase the incidence of overt and subolinical hypothyroidism, and also influence outcome of subclinical hypothyroidism.
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Objective To perform a follow-up survey about thyroid disorders in three rural communities with different iodine intakes in China,observe the incidences and natural outcomes of positive thyroid autoantibodies in euthyroid population,and also explore the influence of iodine intakes on these outcomes and autoantibodies.Methods In 1999,a cross-sectional study on thyroid disorders was performed in three rural communities of Pansan ( mild iodine deficient area),Zhangwu ( more than adequate iodine intake area) and Huanghua (excessive iodine intake area) in China.The 5-year follow-up study was performed in 2004.Both in 1999 and 2004,serum levels of TSH,thyroid peroxidase antibody (TPOAb) and thyroglobulin antibody (TgAb) were measured with the same method.Iodine in urine and B ultrasound on thyroid were also examined.Results Among the euthyroid subjects with normal TSH level in 1999,an increased prevalence of positive TPOAb in Zhangwu and an increased prevalence of positive TgAb in Hnanghua were observed in 2004 (both P＜0.05 ).Most of euthyroid subjects with positive TPOAb or positive TgAb in 1999 remained positive thyroid antibodies in 2004. The percentage was even higher in those with high levels of antibodies.Thyroid dysfunction was more frequent in subjects with positive TPOAb and/or TgAh than in those without thyroid antibodies (14.44% vs 3.11%,P＜0.01).For those with positive antibodies in 1999,the incidence of hypothyroidism in 2004 was 1.32%,8.46% and 15.38% in Pansan,Zhangwu and Huanghua,respectively (P＜0.05).The 5-year cumulative incidences of positive TPOAb (≥50 U/ml) and TgAb (≥40 U/ml) were 2.81% and 3.82%,respectively.The incidence of positive TPOAb was the highest in Zhangwu ( 3.84% ).The incidence of positive TgAb was the highest in Huanghua (5.07%),significantly higher than those in other two areas (P＜0.05).Conclusion The incidence of thyroid dysfunction is higher in subjects with positive antibodies than that in those with negative antibodies.The high iodine intake is a risk factor of hypothyroidism in subjects with positive thyroid antibodies.Sustained excessive iodine intake increases the incidence of positive thyroid antibodies.
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Objective To evaluate the relationship between iodine intake level and the occurrence and development of thyroid diseases.Methods During the period of 1999-2004,a cross-sectional survey in 1999 and a 5-year follow-up survey were conducted in the 3 communities with different iodine intake levels in China:Panshan (mild deficiency),Zhangwu (more than adequate) and Huanghua (iodine excess).A total of 3 761 subjects were included in 1999 and 80.24% of them participated in the 5-year follow-up survey in 2004.The levels of serum thyroid hormones and thyroid autoantibodies were measured,and thyroid B ultrasound was performed.Results (1) The prevalence of overt hypothyroidism in 1999 in Zhangwu and Huanghua was 3.5 and 7.3 times,and that of subclinical hypothyroidism was 3.2 and 6.6 times as high as in Panshan,respectively.The 5-year cumulative incidence of subclinical hypothyroidism was 11.3 and 12.6 times as high as in Panshan,but no difference of incidence of overt hypothyroidism was found.(2) The prevalence of autoimmune thyroiditis (AIT) in 1999 in Zhangwu and Huanghua was 3.8 and 6.2 times,and the S-year cumulative incidence of AIT was 4.4 and 5.5 times as high as in Panshan.(3) During the 5-year follow-up period,the incidences of hypothyroidism in subjects with positive thyroid peroxidase antibody and euthyreidism in Zhangwu and Huanghua were 4.2 and 10.3 times as high as in Panshan.(4) No significant differences in both prevalence in 1999 and 5-year cumulative incidence of overt hyperthyroidism were found in the 3 communities.(5) The incidence of thyroid cancer was 19.37/100 000 per year in Huanghua,and all of the cases were papillary thyroid cancer,and no thyroid cancer was found in Zhangwu and Huanghua.Conclusion More than adequate or excessive dietary iodine intake may induce and promote the occurrence and development of hypothyroidism and AIT,therefore,median urinary iodine excretion (MUI)more than 200?g/L in the population appears not safe.The observation that a higher incidence of thyroid cancer occurred in the iodine excessive areas with MUI 600?g/L deserves further investigation.