Thyroid Therapy for Mild Thyroid Deficiency in Pregnancy

Study Results

Results available

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Basic Information

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Recruitment Status

COMPLETED

Clinical Phase

PHASE3

Total Enrollment

1203 participants

Study Classification

INTERVENTIONAL

Study Start Date

2006-10-31

Study Completion Date

2015-10-31

Brief Summary

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The purpose of this study is to determine whether treating women, who are diagnosed with a mild imbalance of thyroid hormones during pregnancy, with thyroid hormone replacement affects their children's intellectual development at 5 years of age.

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Detailed Description

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Published research reports have stimulated national and international controversy regarding the value of maternal thyroxine therapy given to improve neurodevelopment of the fetus in women with variously defined hypothyroidism. These reports have led to conflicting and confusing recommendations as to whether or not all pregnant women in the U.S. should be screened for subclinical hypothyroidism or hypothyroxinemia.

Pregnant women less than 20 weeks gestation will have a blood test to screen for subclinical hypothyroidism or hypothyroxinemia. If eligible for the trial, patients will receive levothyroxine or placebo until delivery. Blood draws will be done at monthly study visits and the dosage will be adjusted based on test results. The children of these patients will have developmental testing done annually until they are 5 years of age.

Comparison(s): thyroxine supplementation versus placebo given during pregnancy to determine whether therapy is effective in improving intellectual ability at 5 years of age.

Conditions

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Subclinical Hypothyroidism Hypothyroxinemia Pregnancy

Study Design

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Allocation Method

RANDOMIZED

Intervention Model

SINGLE_GROUP

Primary Study Purpose

TREATMENT

Blinding Strategy

TRIPLE

Participants Caregivers Investigators

Study Groups

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Levothyroxine for Subclinical Hypothyroidism

100 µg of Levothryoxine for participants with subclinical hypothyroidism

Group Type EXPERIMENTAL

Levothyroxine

Intervention Type DRUG

Coded study drug is thyroxine encapsulated in a gel capsule; matching placebo contains only cellulose. Color of capsule corresponds to mcg dose level (100mcg or 25 mcg). Subjects in subclinical hypothyroidism stratum are started on 1 capsule of 100 mcg per day; subjects in hypothyroxinemia stratum are started on 2 capsules of 25 mcg per day. Thyroxine dosing adjustments for both strata are determined centrally, using an algorithm, based on results of monthly TSH or free-T4 assays. Subjects take study medication until delivery.

Placebo for Levothyroxine - Subclinincal Hypothyroidism

Placebo for Levothyroxine for participants with subclinical hypothyroidism

Group Type PLACEBO_COMPARATOR

Placebo for Levothyroxine

Intervention Type DRUG

Levothyroxine for Hypothyroxinemia - Hypothyroxinemia

50 µg of Levothyroxine for participants with hypothyroxinemia

Group Type EXPERIMENTAL

Levothyroxine

Intervention Type DRUG

Coded study drug is thyroxine encapsulated in a gel capsule; matching placebo contains only cellulose. Color of capsule corresponds to mcg dose level (100mcg or 25 mcg). Subjects in subclinical hypothyroidism stratum are started on 1 capsule of 100 mcg per day; subjects in hypothyroxinemia stratum are started on 2 capsules of 25 mcg per day. Thyroxine dosing adjustments for both strata are determined centrally, using an algorithm, based on results of monthly TSH or free-T4 assays. Subjects take study medication until delivery.

Placebo for Levothyroxine

Placebo for Levothyroxine for participants with hypothyroxinemia

Group Type PLACEBO_COMPARATOR

Placebo for Levothyroxine

Intervention Type DRUG

Interventions

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Levothyroxine

Coded study drug is thyroxine encapsulated in a gel capsule; matching placebo contains only cellulose. Color of capsule corresponds to mcg dose level (100mcg or 25 mcg). Subjects in subclinical hypothyroidism stratum are started on 1 capsule of 100 mcg per day; subjects in hypothyroxinemia stratum are started on 2 capsules of 25 mcg per day. Thyroxine dosing adjustments for both strata are determined centrally, using an algorithm, based on results of monthly TSH or free-T4 assays. Subjects take study medication until delivery.

Intervention Type DRUG

Placebo for Levothyroxine

Intervention Type DRUG

Eligibility Criteria

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Inclusion Criteria

* Subclinical Hypothyroidism as defined by an elevated TSH (≥ 3.00 mU/L) and a free-T4 in the normal range (i.e. 0.86 to 1.90 ng/dL) or Hypothyroxinemia as defined by a TSH in the normal range (0.08 to 2.99 micrometers (mU)/L) and a low free-T4 (\<0.86 ng/dL)
* Singleton Pregnancy
* Gestational age at randomization between 8 weeks 0 days and 20 weeks 6 days

Exclusion Criteria

1. Major fetal anomaly or demise
2. Planned termination of the pregnancy
3. History of thyroid cancer or current thyroid disease requiring medication
4. Diabetes, on medication (insulin, glyburide)
5. Collagen vascular disease (autoimmune disease), such as lupus, scleroderma and polymyalgia rheumatica, on medication
6. Receiving anticoagulant therapy
7. Depression, currently on treatment with tricyclics or selective serotonin reuptake inhibitors (SSRIs)
8. Other known serious maternal medical complications including:

1. Chronic hypertension requiring antihypertensive medication (including diuretics)
2. Epilepsy or other seizure disorder, on medication
3. Active or chronic liver disease (acute hepatitis, chronic active hepatitis) with persistently abnormal liver enzymes
4. Cancer (including melanoma but excluding other skin cancers)
5. Heart disease (tachyrhythmia, class II or greater heart disease or on heart medication). Mitral valve prolapse without arrhythmia is not an exclusion.
6. Asthma, on oral corticosteroids
9. Known illicit drug or alcohol abuse during current pregnancy
10. Delivery at a non-network hospital
11. Participation in another intervention study that influences maternal and fetal morbidity and mortality, or participation in this trial in a previous pregnancy
12. Unwilling or unable to commit to 5 year follow-up of the infant

Eligible Sex

FEMALE

Accepts Healthy Volunteers

Yes