正常甲状腺功能人群血清促甲状腺激素变化的五年随访研究

目的 探讨正常甲状腺功能者5年随访时促甲状腺激素(TSH)的异常率和影响这一人群TSH发生异常的因素.方法 3个不同碘营养背景的农村社区的3403例甲状腺功能正常者中,80.1%(2727例)接受了筛查后的5年随访,测定其血清TSH和甲状腺自身抗体水平.结果 随访对象中,68例(2.5%)TSH异常降低(<0.3 mU/L),64例(2.4%)TSH异常增高(>4.8 mU/L).logistic回归分析显示,初访时甲状腺过氧化物酶抗体(TPOAb)阴性而随访时阳性(OR=5.5)、初访和随访TPOAb均阳件(OR=4.0)、随访时甲状腺球蛋白抗体(TgAb)阳性(OR=3.7)和初访时TSH<1.0 mU/L(OR=2.6)是TSH异常降低的危险因素;而缺碘基础上补碘至碘足量(OR=4.8)、长期碘过量(OR=3.9)、随访时TgAb阳性(OR=3.7)、初访和随访TPOAb均阳性(OR=3.6)、初访时TPOAb阴性而随访时阳性(OR=2.7)和TSH>1.9 mU/L(OR=2.6)是TSH异常增高的危险因素.结论 与轻度碘缺乏相比,碘足量和碘过量足TSH由正常转为异常升高的危险因素,缺碘基础上补碘至碘足量导致TSH转为异常升高的危险性更高于长期碘过量.初访TSH处于1.0～1.9 mU/L时,5年随访时发生TSH异常的几率最小.

The changes of thyrotropin level in euthyroid population:a 5-year follow-up study in communities with different iodine intakes

Objective To determine the factors that influence the development of abnormal thyrotropin (TSH) level in an euthyroid population.Methods We conducted a follow-up study in 3 communities with different iodine status.Of the 3403 euthyroid subjects at baseline screened in 1999,80.1% ( n = 2727 ) was visited and sampled in 2004 for measuring TSH,thyroid peroxidase antibody (TPOAb) and thyroglobulin antibody (TgAb).Results Iodine status in the 3 communities were stable.Decreased TSH level( <0.3 mU/L) developed in 2.5% (n =68) of sampled subjects,while raised TSH level( > 4.8 mU/L) in 2.4% (n = 64).A logistic analysis showed that risk factors for developing decreased TSH level included positive conversion of TPOAb (OR = 5.5 ),positive TPOAb both in 1999 and in 2004 ( OR = 4.0),positive TgAb in 2004 ( OR = 3.7) and TSH < 1.0 mU/L in 1999 ( OR = 2.6).Risk factors involved in developing raised TSH level included iodine status of Zhangwu community ( OR = 4.1 ),iodine status of Huanghua community ( OR = 3.9),positive TgAb in 2004 ( OR = 3.7 ),positive TPOAb both in 1999 and 2004 (OR =3.6),positive conversion of TPOAb (OR =2.7) and TSH > 1.9 mU/L in 1999 (OR = 2.6 ).Conclusions Exposure to long-term iodine excess imposes danger of developing hypothyroidism.The risk will be even higher when exposing to iodine adequacy after correction of iodine deficiency.An interval between 1.0 and 1.9 mU/L of TSH level was optimul with the least probability of developing abnormal TSH level.