Changes of iodine nutrition status and thyroid function among pregnant women in iodine sufficient rural area of Gansu province / 中华流行病学杂志

ABSTRACT

Objective To assess the iodine nutrition and thyroid function of pregnant women during different periods of pregnancy,to provide evidence for guiding iodine supplementation for them.Methods A cross-sectional survey was performed in 215 pregnant women in Yongjing couty from May to June 2013.Samples of blood and random urine were collected,and serum thyrotrophin (TSH),free triiodothyronine (FT3),free thyroxine (FT4),anti-thyroid peroxidase (anti-TPO),antithyroglobulin (anti-TG) and urinary iodine were measured.Results The medians of urinary iodine from the three groups of pregnant women (first,second and third trimester) were 189.8 μg/L,152.5 μg/L and 144.9 μg/L respectively.With the exception of pregnant women in the third trimester,the urinary iodine medians of pregnant women in the first and second trimesters were within the 150-249 μg/L range which was defined as optimal by WHO/UNICEF/ICCIDD.With the increase of gestational age,the level of FT3 decreased (P＜0.05),with the FT3 levels in the first trimester were higher than those in the second or third trimester (P＜0.05).The difference of TSH levels among the three groups of pregnant women was statistically significant (P＜0.01),with a U-shaped curve seen between the iodine TSH levels and the gestational age.The medians of anti-TG and anti-TPO appeared the lowest in the first trimester,and remained at a high level in women at second and third trimesters.Significant diffierence was seen in anti-TG,anti-TPO levels of the three groups of pregnant women (first,second and third trimester) (P＜0.01).The incidence of thyroidfunction disorder was 1.86％,including subclinical hypothyroidism accounted for 1.40％,and hypothyroidism accounted for 0.47％.The incidence of thyroidfunction disorder mainly appeared in the early pregnancy.Abnormal FT3,TSH,positive anti-TG and anti-TPO were mainly seen during early pregnancy.The changes of TSH,FT3,FT4,anti-TG and anti-TPO along with the changes of urine iodine levels were not obvious.Conclusion With the increase of gestational age,the incidence of iodine deficiency also increased among pregnant women.Abnormal thyroid hormones,TSH,positive anti-TG and anti-TPO were mainly existed in the early pregnancy.Programs as monitoring urinary iodine as well as thyroid function targeting all the pregnant women should be carried out.