The Relationship between Different Iodine Intake and Thyroid Function in Adults

Objective: To observe the effect of different iodine intake on the thyroid function in euthyroid adult persons. Methods: One hundred and sixty-one euthyroid healthy volunteers aged 18-24 years were randomly divided into 7 groups. Each group was assigned to receive 500 μg, 750 μg, 1 000 μg, 1 250 μg, 1 500 μg, and 2 000 μg iodide/day for four weeks. Serum concentrations of free triiodothyronine(FT3), free thyroxin(FT4) and sensitive thyroid-stimulating hormone (sTSH) were measured by chemoluminescence assays. Results: Serum FT3 concentration was found a small decline within the normal range in all the iodide supplemented groups (P 0.05). The level of FT4 was significantly lower, when the dose was up to 1 500 μg (P 0.05). The level of serum sTSH was increased after 2 weeks iodide supplement in all groups, and after 4 weeks in 500 μg and 750 μg groups(P 0.05). No significant changes were observed in FT3,FT4 and sTSH between groups(P 0.05). Conclu- sion: The thyroid function of normal people showed a rise in serum sTSH at a short time and a high-dose of iodine intake.