Normal Range of TSH and FT4 in Pregnancy

Study Overview
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Brief Summary
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Physiological changes necessitate the use of pregnancy-specific reference ranges for thyrotrophin (TSH) and free T4 (FT4) to diagnose thyroid dysfunction during pregnancy. Although many centers use fixed upper limits for TSH of 2.5 or 3.0 mU/L, this may lead to overdiagnosis or even overtreatment. The new guidelines of the American Thyroid Association have considerably changed recommendations regarding thyroid function reference ranges in pregnancy accordingly. Any hospital or physician that is still using the 2.5 or 3.0 mU/l cut-off for TSH during pregnancy should evaluate their own lab-specific cut-offs. The investigator's objective is to establish a rational reference range of serum TSH for the diagnosis of subclinical hypothyroidism in the first, second, and third trimester of pregnant women in the Sancaktepe region in Turkey.

Detailed Description
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Serum thyroid function tests (including T3, T4, TSH, Anti-TPO) will be obtained from the singleton pregnancies in the first, second, and third trimester to determine the local specific normal ranges.

Official Title
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Normal Range of TSH and FT4 in Pregnancy

Conditions
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Hypothyroidism, Pregnancy Related, Thyroid, Dysfunction, Iodine Deficiency

Intervention / Treatment
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* Diagnostic Test: Serum thyroid function tests


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Singleton pregnancy Free of pre-existing thyroid disease That do not use thyroid interfering medication That did not undergo IVF treatment TPOAb negative Exclusion Criteria: Adolescent pregnancy Patient with pre-existing thyroid disease TPOAb positive Patient using thyroid interfering medication That had IVF treatment

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 50 Years

Sexes Eligible for Study
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Female

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Pregnant women<br>500 pregnant women with a singleton pregnancy, free of pre-existing thyroid disease, that do not use thyroid interfering medication, that did not undergo IVF treatment, and are TPOAb negative. Serum thyroid function tests will be obtained on the first visit. | Diagnostic Test: Serum thyroid function tests<br>* At the first hospital visit, the blood tests will be made for TSH, FT4, FT3, and beta HCG concentration measurement<br>* Other names: Thyroid ultrasonography;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| TSH | Trimester specific TSH level | On day 1 | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| free T4 | Trimester specific free T4 level | On day 1 | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Hypothyroidism, Pregnancy, trimester, thyroid dysfunction, iodine level