妊娠前半期甲状腺功能减退症的临床流行病学调查

目的 调查中国汉族碘适量地区正常育龄妇女妊娠前半期甲状腺功能减退症(甲减)的患病率.方法 妊娠前半期妇女共4 800人人选,测定血清TSH、FT4和甲状腺过氧化物酶抗体(TPOAb)水平.以妊娠期特异性甲状腺功能正常范围和非妊娠人群甲状腺功能正常范围两种标准,分别筛查甲减.结果 采用妊娠期特异性甲状腺功能正常范围诊断妊娠4周、8周临床甲减的患病率为1.03%、0.37%,妊娠4周、8周、12周、16周、20周妇女亚临床甲减的患病率分别为4.59%、6.15%、4.68%、4.53%、5.96%;低T4血症的患病率分别为3.69%、1.11%、2.92%、1.29%、2.29%.如采用非妊娠人群诊断标准,则其亚临床甲减的漏诊率分别为0.18%、2.85%、4.10%、3.24%、3.21%;低T4血症的漏诊率分别为3.45%、0.66%、2.34%、1.29%、1.83%.妊娠4周、8周、16周时亚临床甲减组TPOAb阳性率明显高于甲状腺功能正常组;妊娠4周、8周、12周、16周时TPOAb阳性组亚临床甲减的患病率明显高于TPOAb阴性组.结论 采用妊娠期特异性甲状腺功能评价指标的正常范围,能够降低妊娠前半期亚临床甲减和低T4血症漏诊率.TPOAb阳性是妊娠前半期亚临床甲减发生的主要危险因素之一.

An epidemiologic survey of hypothyroidism during the first half of pregnancy

Objective To investigate the prevalence of hypothyrodism during the first half of pregnancy in the Han nationality women in iodine-adequate area. Methods TSH, FT4 and thyroid peroxidase antibody (TPOAb) levels were detected in 4 800 pregnant women during the first half of pregnancy. Both gestational age-specific reference intervals and population-based reference intervals of thyroid function were applied and the corresponding prevalences of hypothyroidism were compared with each other. Results Based on the gestational age-specific reference intervals, the prevalences of overt hypothyroidism at 4th and 8th weeks of gestation were 1.03%, 0.37% respectively. At 4th, 8th, 12th, 16th and 20th weeks of gestation, the prevalences of subclinical hypothyroidism were 4.59%, 6.15% , 4.68%, 4.53%, 5.96% respectively, while those of hypothyroxinemia were 3.69%, 1.11%, 2.92% , 1.29%, 2.29%, respectively. According to the pepulation-based reference intervals, the rates of missed diagnosis of subclinical hypothyroidism were 0.18%, 2.85%, 4.10%, 3.24%, 3.21% while those of hypothyroxinemia were 3.45%, 0.66%, 2.34%, 1.29%, 1.83%, respectively. During 4th, 8th, 16th weeks of gestation, the positive rates of TPOAb in the group with subclinical hypothyroidism were significantly higher than those with euthyroidism. The prevalences of subclinical hypothyroidism in TPOAb positive group were obviously higher than those in TPOAb negative group at 4th, 8th, 12th, 16th gestational weeks. Conclusion The rates of missed diagnosis of subclinical hypothyroidism and hypothyroxinemia during the first half of pregnancy were decreased by applying the gestational age-specific reference intervals in this prospective study. Positive TPOAb is a risk factor for subclinical hypothyroidism during the first half of pregnancy.