Effects Of Iodine Excess On Maternal And Neonates’Thyroid Function

Objective1. To evaluate the pregnant women’s iodine nutrition status in Haixing County and Tianjin City.2. To know well about women and neonates’ thyroid function and thyroid autoimmunity.3. To explore relationship among iodine excess, thyroid function and thyroid autoimmunity, providing theoretical basis for high iodine prevention and cure.4. To explore effects on neonates’growth and development of different iodine intake.Methods1. Haixing and Tianjin were identified as investigated areas based on water iodine monitoring data. Tianjin was next to Haixing and had mainly eliminated iodine deficiency.2. We collected pregnant women aged18～45in Haixing County Hospital and Tianjin Central Hospital of Gynecology Obstetrics. Inclusion criteria were as follows:Women had no endocrine diseases, other autoimmune diseases, heart diseases and family genetic diseases, lived locally over5years, and used nothing with iodine.3. We recorded demographics and sign informed consent forms.4. Pregnant women’s midstream urine, venous blood and neonates’cord blood were collected. Urinary iodine was measured by national standard methods, FT3, FT4and sTSH by chemiluminescence immunoassay, and TPOAb and TGAb by radioimmunoassay.Results1. Urinary iodine medians in210pregnant women of excessive iodine and in174women of adequate iodine were1240.70μg/L and217.06μg/L, which were iodine excess and adequate.2. Pregnant women and neonates of excessive iodine had higher FT3, sTSH, and lower FT4than those of adequate iodine (P<0.05).3. Prevalence of thyroid disease especially subclinical hypothyrodism in pregnant women of excessive iodine was higher than that in those of adequate iodine (P<0.05). sTSH in neonates of excessive iodine distribute higher than that in those of adequate iodine (P<0.05).4. No differences were found in women and neonates’thyroid autoantibodies’ positive rates (P>0.05).5. Thyroid autoantibodies’positive rate in women with thyroid disease especially subclinical hypothyroidism and neonates had higher tendencies than that in those without thyroid diseases in excessive iodine area, but no statistical difference (P>0.05). So did the tendency of neonates’sTSH distribution, and statistically different (P<0.05).6. No differences were found in thyroid hormones of different thyroid autoimmunities women and neonates in the same area (P<0.05). For population with the same thyroid autoimmunity, pregnant women’s thyroid diseases especially subclinical hypothyroidism prevalence and neonates’ FT3, sTSH of excessive iodine were higher and FT4was lower than those of adequate iodine; pregnant women’s FT3, sTSH were higher and FT4was lower than those of adequate iodine; neonates’ratio of sTSH<5mIU/L was lower and ratio of sTSH>10mIU/L was higher than those of adequate iodine (P<0.05).7. sTSH and thyroid autoantibodies’positive rates were positive relative between women and neonates in the same area (P<0.05).8. Risk factors for pregnant women’s subclinical hypothyroidism and neonates’ thyroid dysfunction were excessive iodine (odds ratio=26.535, P<0.05), and excessive iodine (odds ratio=10.738, P<0.05) and abnormal pregnancy outcomes (odds ratio=3.179, P<0.05).9. Neonates’birth weights and biparietal diameters in high iodine area were higher and femur lengths were lower than those in adequate area (P<0.05). Neonates’biparietal diameters with no thyroid disease mothers were higher than those with thyroid disease especially subclinical hopythyroidism mothers (P<0.05).Conclusions1. Pregnant women investigated in high iodine area were in the status of iodine excess, indicating they should change drinking water and ensure adequate iodine intake.2. Iodine excess could increase the risk of thyroid diseases especially subclinical hypothyroidism, and affect neonates’thyroid function, elevating their TSH levels.3. Iodine excess with positive thyroid autoantibodies of pregnant women could considerably affect neonates.4. Maternal and neonates’ positive rates may increase with urinary iodine, which should be monitored.5. Neonates’thyroid function and growth and development whose mothers had thyroid disease should be cared. Effects on neonates’growth and development of iodine excess should be further studied.