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Thyroid UK
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Is iodine useful to lift T4 levels


My results of thyroid function (done privately) are...

TSH 3.52 (range .27 - 4.2)

T4 12.4 (range 12.0 - 22.0)

Free T3 4.9 (range 3.9 - 6.8)

Is it useful for me to take 150mcg iodine pills (twice a day) to lift T4? Presumably I need to also take selenium at the same time.

I have and NHS doc appointment in August where I will take my results and hopefully get further meds as needed to increase the T4 (despite TSH being ok)

I am very new to all this but increasingly eager to alleviate all my symptoms.


7 Replies


Iodine used to be used as a treatment to reduce FT4 and FT3 in hyperthyroid patients so unless you are iodine deficient I wouldn't supplement iodine. It may be helpful to supplement 200mcg selenium.

Are you taking Levothyroxine?


I haven't been prescribed anything yet. I have already bought selenium supplements though so will start on those. Thank you!



Your thyroid gland is failing but NHS won't usually diagnose hypothyroidism and commence Levothyroxine replacement until TSH is >4.2 or FT4 <12.0.

Your FT4 is very low in range so it may be worth retesting in 6 months. Arrange the blood draw early in the morning when TSH is highest and fast (water only) as TSH drops after eating and drinking.

Your GP may not agree to test thyroid peroxidase antibodies until TSH is over range.


Many thanks. Al this info is so helpful as I learn about such a complex thing!


Would be good idea to test thyroid antibodies for autoimmune thyroid disease, also known as Hashimoto's

Also testing for low levels of vitamin D, folate, B12 and ferritin.

Iodine is definitely not recommended for anyone with Hashimoto's. Even avoid any multivitamin with iodide in.


Thank you. Thats more info to take to the docs to see what they are prepared to do.

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