Screening of Hypothyroidism of Women during the First Half of Pregnancy in Qingdao

Objective: To observe the occurrence of hypothyroidism during the first half of pregnancy in women in Qingdao.Methods: 338 pregnant women and 94 non-pregnant women were collected.Urinary iodine excretion and serum thyrotropin(TSH),Free thyroxine(FT4),thyroid peroxidase antibody(TPOAb) levels were determined in all subjects.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 pregnant age-specific reference intervals,the prevalence of overt hypothyroidism at 8th weeks of gestation was 1.71%;at 8th,12th,16th and 20th weeks of gestation,the prevalences of subclinical hypothyroidism were 4.00%,3.17%,2.27%,3.57%,respectively;the prevalences of hypothyroxinemia were 6.29%,4.76%,2.27%,10.71%,respectively.According to the non-pregnant reference intervals,during the 8th weeks of gestation,the rates of missed diagnosis of overt hypothyroidism was 1.14%.The rates of missed diagnosis of the subclinical hypothyroidism were 2.29%,1.59%,2.27%,3.57% at 8th,12th,16th and 20th weeks of gestation,respectively.The rate of missed diagnosis hypothyroxinemia was 4.00% at the 8th weeks of gestation and 3.17% at 12th weeks of gestation.The miagnosis rates of hypothyroxinemia were 22.73% and 33.93% at 16th and 20th weeks of gestation.At 8th 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.Conclusion: According to the gestational month-specific reference intervals can decrease the rate of missed diagnosis of subclinical hypothyroidism and the misdiagnosis rate of hypothyroxinemia.Positive TPOAb is one of the risk factors for subclinical hypothyroidism.