Research on Association Between Selenium Deficiencies and Change of Thyroid Function

Study Overview
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Brief Summary
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As one of the essential micronutrients, selenium has important biological functions. However, an effective and convenient method for evaluation of selenium nutritional status has not yet been established. Previous literature has disclosed effect of selenium deficiency on inactivating glutathion peroxidase and deiodinase, which may cause decreased conversion from thyroxine ( T4) to triiodothyronine (T3). A case-control study is designed to demonstrate the association between selenium deficiency and abnormally elevated T4 or T4/T3, which may provide more clues for establishing effective selenium assesment methods.

Official Title
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Effect of Selenium Deficiency on Thyroid Function

Conditions
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Selenium Deficiency

Intervention / Treatment
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* Diagnostic Test: detection of serum selenium


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: with normal free triiodothyronine( FT3), free thyroxine (FT4) and thyroid-stimulating hormone (TSH). without thyroid hormone replacement therapy without medical history of thyroid surgery without iodine radiotherapy; Exclusion Criteria: acute critical illness in the latest 1 year; weight fluctuation by more than 5% in the latest 3 months; eating disorders neuropsychological disorders allergy to corn or yeast fail to give informed consents.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 80 Years

Sexes Eligible for Study
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All

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 |
| --- | --- |
| group with normal T4 level or T4/T3<br>participants with T4 within 4.3-12.5ug/dl and ratio of T4/T3(T4(ug/dl)/T3 (ng/ml)) ≤7.52, which are considered to be normal T4 level and T4/T3. | Diagnostic Test: detection of serum selenium<br>* For this case-control study, no intervention will be administered to participants, only serum sample will be collected for selenium assessment<br>|
| group with elevated T4 level or T4/T3<br>participants with T4 more than 12.5ug/dl and ratio of T4/T3(T4(ug/dl)/T3 (ng/ml)) > 7.52, which are considered to be elevated T4 level and T4/T3. | Diagnostic Test: detection of serum selenium<br>* For this case-control study, no intervention will be administered to participants, only serum sample will be collected for selenium assessment<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| between-group difference in serum selenium | comparison of the mean serum selenium between the two groups | up to 24 weeks | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| between-group difference in serum deiodinase activity | comparison of the mean deiodinase activity between the two groups | up to 24 weeks | 
| between-group difference in erythrocyte glutathione peroxidase activity | comparison of the mean erythrocyte glutathione peroxidase activity between the two groups | up to 24 weeks |