Studies related to Serum T4 and Iodine

Effect Of Low Dose Iodide Supplementation On Thyroid Function In Potentially Susceptible Subjects: Are Dietary Iodide Levels In Britain Acceptable

Effect Decrease
Trial Design Double blind
Trial Length 2-4 Weeks
Number of Subjects 300
Gender Female
Age Range 18-29, 30-44, 45-64
Body Types Average
Notes for this study:
500mcg of iodine in persons with subclinical Hashimoto's disease (reaching a daily intake of 750mcg due to 250mcg in the diet) was able to slightly suppress circulating T4 and increase in TRH (thyrotropin releasing hormone) although no subject developed hypothyroidism.

Effects Of Low Dose Oral Iodide Supplementation On Thyroid Function In Normal Men

Effect Decrease
Trial Design Double blind
Trial Length 1-2 Weeks
Number of Subjects 30
Gender Male
Age Range 18-29, 30-44
Body Types Average
Notes for this study:
Supplementation of iodine for two weeks in otherwise healthy men increased TSH levels in serum, and while 500mcg was unable to influence active thyroid hormones the higher tested doses of 1,500-4,500mcg suppressed them.

Effects Of Low Dose Oral Iodide Supplementation On Thyroid Function In Normal Men

Effect None
Trial Design Double blind
Trial Length 1-2 Weeks
Number of Subjects 30
Gender Male
Age Range 18-29, 30-44
Body Types Average
Notes for this study:
Supplementation of iodine for two weeks in otherwise healthy men increased TSH levels in serum, and while 500mcg was unable to influence active thyroid hormones the higher tested doses of 1,500-4,500mcg suppressed them.

Breast-milk Iodine Concentration Declines Over The First 6 Mo Postpartum In Iodine-deficient Women

Effect None
Trial Design Double blind
Trial Length 1-6 months
Number of Subjects 109
Gender Female
Age Range 18-29, 30-44
Body Types Obese, Overweight
Notes for this study:
Supplementation of iodine (75-150mcg) daily for 24 weeks to pregnant women over the course of 24 weeks was able to increase urinary and breast milk concentrations of iodine, but did not influence T4 nor thyrotropin concentrations in serum.

The Effect Of Small Increases In Dietary Iodine On Thyroid Function In Euthyroid Subjects

Effect Decrease
Trial Design Double blind
Trial Length 1-2 Weeks
Number of Subjects 32
Gender Both Genders
Age Range 18-29, 30-44
Body Types Average
Notes for this study:
In persons with normal thyroid function given 1,500mcg iodine daily for two weeks, there was a reduction in active thyroid hormones and increase in TSH; this was not seen with 250-500mcg daily.