妊娠晚期妇女甲状腺疾病特点及甲状腺自身抗体变化的研究

目的 探讨妊娠晚期妇女甲状腺疾病的患病率、患病特点和甲状腺自身抗体的变化.方法 选择664例妊娠晚期妇女为妊娠组,276例非妊娠育龄妇女作为对照组.应用固相化学发光酶免疫法测定两组妇女的血清促甲状腺激素（TSH）和抗甲状腺过氧化物酶抗体（TPOAb）水平;TSH水平检测异常者加测游离甲状腺素（FT4）和游离三碘甲状腺原氨酸（FT3）,同时测定尿碘水平.按如下标准确定诊断：TSH＜0.3 mU/L,FT4和（或）FT3水平升高者诊断为临床甲状腺功能亢进症（甲亢）;TSH＜0.3 mU/L,而FT4和FT3水平正常者诊断为亚临床甲亢;TSH＞4.8 mU/L,FT4水平降低者诊断为临床甲状腺功能减退症（甲减）;TSH＞4.8 mU/L,而FT4和FT3水平正常者诊断为亚临床甲减.TPOAb＞5 kU/L为阳性.结果 （1）妊娠组妇女尿碘平均水平为201.5μg/L,对照组妇女尿碘平均水平为196.0μg/L,均为碘充足水平.两组比较,差异无统计学意义（P＞0.05）.（2）妊娠组妇女甲状腺疾病总患病率为7.8%（52/664）,对照组妇女甲状腺疾病总患病率为6.9%（19/276）.两组比较,差异无统计学意义（P＞0.05）.（3）两组妇女的甲状腺患病类型有明显不同,妊娠组妇女甲亢患病率为1.1%（7/664）,甲减患病率为6.8%（45/664）,妊娠组妇女甲亢患病率明显低于甲减,两者比较,差异有统计学意义（P＜0.01）;对照组甲亢患病率为4.7%（13/276）,甲减患病率为2.2%（6/276）,两者比较,差异无统计学意义（P＞0.05）.妊娠组与对照组妇女的甲亢或甲减患病率分别比较,差异均有统计学意义（P＜0.01）.（4）妊娠组非患病妇女的TSH水平显著高于对照组,分别为2.50 mU/L及1.54 mU/L,差异有统计学意义（P＜0.01）;妊娠组妇女TPOAb阳性率显著低于对照组,分别为3.3%（22/664）及9.4%（26/276）,差异有统计学意义（P＜0.01）.结论 妊娠晚期妇女甲状腺疾病的特点是甲减的患病率高,同时甲状腺自身免疫功能受到抑制.

Thyroid function and thyroid autoimmunity at the late pregnancy: data from 664 pregnant women

OBJECTIVE: To study the prevalence of thyroid diseases, as well as characteristics of the disease spectrum and thyroid autoimmunity in women at the end of pregnancy. METHODS: Six hundred and sixty-four pregnant women (pregnancy group) and 276 non-pregnant women (control group) were enrolled in the study. Serum thyrotropin (TSH), thyroid peroxidase antibody (TPOAb), free T(3) (FT(3)) and free T(4) (FT(4)) were measured by high-sensitive immunochemiluminescent assay, and urinary iodine was also examined at the end of pregnancy. Overt hyperthyroidism was diagnosed when both TSH < 0.3 mU/L and FT(4) and/or FT(3) levels were elevated. Subclinical hyperthyroidism was diagnosed when TSH < 0.3 mU/L with normal FT(4) and FT(3) levels. The diagnostic criteria for overt hypothyroidism was TSH > 4.8 mU/L accompanied by decreased FT(4), and for subclinical hypothyroidism was TSH > 4.8 mU/L with normal FT(4) and FT(3) levels. RESULTS: (1) The median urinary iodine (MUI) of pregnancy group was 201.5 microg/L, and that of control group was 196.0 microg/L (P > 0.05). Women in the two groups were iodine-adequate. (2) The overall prevalence of thyroid diseases in pregnancy group and control group was 7.8% (52/664) and 6.9% (19/276), respectively (P > 0.05). (3) As for the diseases pattern, there were obvious differences between the two groups. In pregnancy group, the prevalence of hyperthyroidism was lower than that of hypothyroidism (1.1% vs 6.8%, P < 0.01). In control group, the prevalence of hyperthyroidism and hypothyroidism was 4.7% and 2.2%, respectively (P > 0.05). Compared with control group, the prevalence of hyperthyroidism in pregnancy group was much lower (1.1% vs 4.7%, P < 0.01), mainly due to the decrease of overt hyperthyroidism; whereas, the increment of subclinical hypothyroidism resulted in the higher prevalence of hypothyroidism in pregnancy group (6.8% vs 2.2%, P = 0.01). (4) The median TSH level of the healthy women in pregnancy group was significantly higher than that in control group (2.50 vs 1.54 mU/L, P < 0.01). The positive rate of TPOAb in pregnancy women was lower than that in non-pregnancy women (3.3% vs 9.4%, P < 0.01). CONCLUSION: At the end of pregnancy, hypothyroidism accounts for most thyroid diseases. Thyroid autoimmunity is suppressed.