The clinical research of maternal thyrotoxicosis in the first trimester

Abstract

Objective To study the incidence of maternal thyrotoxicosis in the first trimester and compare thyroid function,clinical manifestations in the first trimester between gestational transient thyrotoxicosis (GTT) and Graves' disease.Methods The subjects were selected from 8 105 pregnant women who had participated in the study of Subclinical Hypothyroid during Early Pregnancy from 2011 to 2013.All subjects received questionnaires,physical examination,and thyroid stimulating hormone (TSH),free T4 (FT4),thyroid peroxidase antibody (TPOAb),urinary iodine measurement,and thyroid ultrasonography during the first trimester (1-12 weeks).Patients with thyrotoxicosis were measured for free T3 (FT3) and thyrotropin receptor antibody (TRAb).71 patients with GTT,32 patients with Graves' disease,and 219 age-matched pregnant women with normal thyroid function in the control group have been followed up during the second trimester(13-27 weeks) and the third trimester(≥28 weeks).Results (1) The incidences of maternal thyrotoxicosis in the first trimester was 1.34％.GTT 0.90％,and Graves' disease 0.44％.(2) The frequency of severe hyperthyroidism signs of patients with Graves' disease was significantly higher than that of patients with GTT(P＜0.05).There were significant difference of body mass index and thyroid volume between GTT or patients with Graves' disease and control group.The thyroid volume and body mass index of patients with GTT and patients with Graves' disease were significantly different with that of control group (P＜0.01).(3) TSH of patients with Graves' disease was significantly lower than that of patients with GTT during pregnancy,while FT4,TRAb,TPOAb of patients with Graves' disease were significantly higher than that of patients with GTT during pregnancy(P＜0.01).FT3 of patients with Graves' disease was significantly higher than that of patients with GTT during the first trimester(P＜0.05).TSH and FT4 of patients with Graves' disease had significantly statistical difference with those of control group during pregnancy (P＜0.01).TSH and FT4 of patients with GTT had significantly statistical difference with those of control group during the first trimester and the second trimester(P＜0.01),but TSH of patients with GTT was significantly lower than that of control group (P＜0.05),and FT4 of patients with GTT had no significantly statistical difference with that of control group during the third trimester.Conclusions GTT is the main causes of thyrotoxicosis in the first trimester.The thyroid function and clinical symptoms of GTT patients and Graves' disease were significant different.During the second and third trimesters the thyroid function of GTT patients returned to normal,but still,most of patients with Graves' disease had increased FT4 and decreased TSH. Key words: Gestational transient thyrotoxicosis; Graves' disease; Thyroid stimulating hormone; Thyroxine