Research On Iodine Nutrition And Thyroid Function Of Pregnant Women In High Water Iodine Areas

Objective:To investigate the characteristics of maternal thyroid function of pregnant women of each stage in high water iodine area. Method:The investigation sites were selected, which were the Hospital for Women and Children of Jinghai county in the high water iodine area (drinking iodine>200μg/L)and the Hospital for Women and Children of Heping district in Tianjin in the adaptive iodine area(drinking iodine<10μg/L, popularization rate of iodine salt >90%, residents urinary iodine>100μg/L).In the maternal and child hospitals,50 pregnant women of each stage from obstetric clinics in first, second, third term of pregnancy and 50 non pregnant women were selected, the blood samples were collected and thyroid function were measured with chemiluminescence.Water, salt and diurnal optional urine samples were measured for iodine concentration. Iodine levels of urine, water, salt were determined respectively by As-Ce catalysis spectrophotometry method, quantitative determining kit which use time-recorded determination by catalytic effect on the As-Ce reaction and sodium hyposulfite titration method. Result:①The difference of thyroid function between pregnant and non pregnant women in high water iodine area and adaptive iodine area have common and special characteristics.②In pregnant women with negative thyroid antibody,serum TT4,TT3,FT4 in first term of pregnancy and FT4,FT3 in second term of pregnancy were significantly lower in high water iodine area than adaptive iodine area(111.97 nmol/L vs 140.46 nmol/L,Z=3.56 P<0.01; 1.86 nmol/L vs 2.26 nmol/L,Z=2.35, P<0.05;14.13 pmol/L vs 16.32 pmol/L,Z=5.14,P<0.01,and 11.98 pmol/L vs 14.30 pmol/L,Z=5.75,P<0.01;4.04 pmol/L vs 4.32 pmol/L,Z=2,76, P<0.01),while TT3 and TSH in third term of pregnancy were significantly higher(2.88 nmol/L vs 2.70 nmol/L,Z=-2.27, P<0.05;2.37 mU/L vs 1.75 mU/L,Z=-2.70,P<0.01).③Concentration of water iodine and urine iodine were higher (205.57μg/L vs 8.26μg/L,Z=-14.71,P<0.01;305.91μg/L vs 191.86μg/L, Z=-5.30,P<0.01),while salt iodine was lower(26.5 mg/kg vs 31.7 mg/kg, Z=5.86,P<0.01)in high water iodine area.④Among 290 selected healthy pregnant women without medical history of thyroid diseases,there was no significant difference in positive rate of thyroid antibody in each term of pregnancy between high water iodine area and adaptive iodine area(10.20% vs 10.64%;14% vs 9.52%;4% vs 7.69% P>0.05).⑤Water iodine, urine iodine to creatinine and TSH in both pregnant and non pregnant women and urine iodine in pregnant women were negatively correlated with FT4.Conclusions:The thyroid function of pregnant women in high water iodine area is different-from pregnant women in adaptive iodine area with universal salt iodization.Enhanced monitor on thyroid function of pregnant women in high water iodine area should be performed, especially in first and second trimester.