The Correlation Between Iodine and Selenium Status in Pregnancy and Risk of Thyroid Disease

Study Overview
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Brief Summary
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Two hundred and ninety pregnant women with gestational age less than 20 weeks will be recruited in this study. Selenium and iodine conditions, and risk of thyroid disease will be monitored until termination of pregnancy, with pregnancy outcomes recorded.

Detailed Description
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The study will recruit 290 pregnant women with gestational age less than 20 weeks. Iodine and selenium condition will be evaluated through dietary recall (on base of Chinese food ingredient information) and biochemical examinations (serum iodine concentrations, urinary iodine concentrations, serum selenium concentrations, etc). The nutritional status of iodine and selenium will be monitored and followed up for all the included subjects throughout the pregnancy. The information of thyroid function and level of anti-TPO and anti-TG will be collected. And all the complications (especially thyroid disease) in pregnancy will also be recorded. All pregnant women will be followed up until the termination of pregnancy, with pregnancy outcomes recorded.

Official Title
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The Correlation Between Iodine and Selenium Status in Pregnancy and Risk of Thyroid Disease: a Prospective Registry Study

Conditions
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Iodine Excess in Pregnancy, Selenium Excess in Pregnancy, Iodine Deficiency in Pregnancy, Selenium Deficiency in Pregnancy

Intervention / Treatment
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* Other: Not applicable (for observational studies)


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Clinical confirmation of being pregnant. Being within less than 20 weeks of gestationa. Exclusion Criteria: Being pregnant but over 20 weeks of gestationa. Mentally or psychologically unstable.
Sexes Eligible for Study
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Female

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Proper selenium and iodine condition<br>The subjects should have proper dietary intake of selenium and iodine, according to Chinese Dietary Reference Intakes (DRIs) (intake of selenium 65μg/d and iodine 230 μg/d). The Serum iodine concentration are 45-92μg/L，and the urinary I/Cr 150-249μg/g Cr. The Serum selenium concentrations are 18-40μg/L. | Other: Not applicable (for observational studies)<br>* This study is an observational study. No intervention will be administered for research purposes.<br>|
| Excessive selenium or iodine condition<br>The subjects have excessive dietary intake of selenium and iodine, usually more than 2 times of DRIs. The Serum iodine concentration are more than 100μg/L，and the urinary I/Cr more than 300μg/g Cr. The Serum selenium concentrations are more than 40μg/L. | Other: Not applicable (for observational studies)<br>* This study is an observational study. No intervention will be administered for research purposes.<br>|
| Insufficient selenium or iodine condition<br>The subjects have insufficient dietary intake of either selenium or iodine, compared with DRIs. The Serum iodine concentration are less than 45μg/L，and the urinary I/Cr less than150μg/g Cr. The Serum selenium concentrations are less than 18μg/L. | Other: Not applicable (for observational studies)<br>* This study is an observational study. No intervention will be administered for research purposes.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| risk of thyroid disease | prevalence of thyroid disease (abnormal thyroid function; development of thyroid antibodies) | From date of participant inclusion until the date of termination of pregnancy, assessed up to 8 months | 
| pregnancy outcomes | prevalence of premature birth, stillbirth and abortion | From date of participant inclusion until the date of termination of pregnancy, assessed up to 8 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| prevalence of other pregnant complications | prevalence of gestational diabetes mellitus, gestational hypertension, dyslipidemia, etc. | From date of participant inclusion until the date of termination of pregnancy, assessed up to 8 months | 
| prevalence of thyroid disease in neonates | prevalence of thyroid disease (abnormal thyroid function; development of thyroid antibodies，or findings of thyroid nodules) in neonates | From date of birth to 4 weeks after birth |