Increase Conversion of T4 to T3: Hello, I have... - Thyroid UK

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Increase Conversion of T4 to T3

darkknightlt profile image

Hello, I have noticed that for the past few years, my labs always comes up with something like: FT4 in the upper range, or slightly above, normal TSH around 1.8, and low end normal FT3. I have recently noticed gaining weight, and feeling more hungry than usual, my doctor told me that it is slight insulin resistance (after tests) and that it relates to thyroid, which is according to her underactive.

I am looking at the following prescription: brown seaweed for iodine, vitamin D 4000 IU and selenium 200mcg every other day. Basically, from her experience, people with high TSH usually have insulin resistance as well. Hence, to reverse the issue, I need to increase conversion of T4 to T3 and metabolic yield of the thyroid.

I was told my problem is not medication-needed but the supplements above could help.

Does this ring any bells to someone in a similar situation?

13 Replies
SeasideSusie profile image


Unless iodine is tested and found to be deficient, it's not recommended to supplement with any kind of iodine supplement (kelp or otherwise). Iodine used to be used to treat hyperthyroidism in the past.

What is your Vit D level, you need to take a dose of D3 appropriate to your level to bring it up to the level recommended by the Vit D Council and Vit D Society.

It was tested last August and was said to be above average normal - vitamin D.

I am not sure how to get iodine levels test, I wonder if NHS covers such things just for finding out because normal GPs see in range thyroid hormones and think all is good. But yeah, I am a bit afraid of adding stuff like the above into the mix since there could be a good reason for lowish FT3 and highish FT4. I don't feel particularly bad, but could swing in either direction with experiments.

SeasideSusie profile image
SeasideSusieAdministrator in reply to darkknightlt

above average normal - vitamin D

What is the actual result, so that you know that you are taking the correct amount of D3? D3 is fat soluble so any excess is stored, take too much and you head towards toxicity level. If your level is between 100-150nmol/L - which is the level recommended by the Vit D Council and the Vit D Society - then you will just need a maintenance dose, and 4000iu is more than a maintenance dose. Are you also taking D3's important cofactors, especially magnesiumand Vit K2-MK7?

Testing current iodine level can be done with a simple urine test with Genova Diagnositics, with ThyroidUK as your "practioner" (they don't deal direct with the public, you order with TUK as your practioner, results are sent to them and TUK send them on to you).

Urine Iodine Test:

Specimen requirements: Urine

Cost: £71.00

Order Code: END25

Turnaround time: 5 - 10 days

Iodine is an essential trace element, vital for healthy thyroid function. Adequate levels are required to enable the production of T3 and T4 thyroid hormones, whilst also being required in other areas of health. Deficiencies can lead to impaired heat and energy production, mental function and slow metabolism. Urine iodine is one of the best measures of iodine status. This test is not performed as a loading test, but can be used to establish existing levels or to monitor iodine supplementation.

The level was 110 and I was taking K2 but no magnesium. I now take 4000 I every other day and have been taking mag citrate for last two months.

Apparently very few people are low in iodine, and taking iodine can actually suppress the thyroid and make you worse!

Who is treating you that she advised/prescribed iodine? That is VERY irresponsible! Surely no proper doctor would prescribe iodine without testing it, especially if you are hypothyroid!!!!

danym profile image
danym in reply to

if my iodine levels are below the bottom range but I have hashimoto, what iodine supplement would be recommended?

in reply to danym

Sorry no idea, but it is very unlikely you are deficient.

danym profile image
danym in reply to

my urine tests showed level below the bottom range :(

in reply to danym

Sorry, I thought you said you hadn't had a test!

"FT4 in the upper range, or slightly above, normal TSH around 1.8, and low end normal FT3"

It sounds as if you are not converting T4 to T3 very well. I don't know if your doctor would prescribe T3 or anything containing T3 but it does seem as if you need it. Your TSH could be a bit lower too.

Have you had selenium tested? Don't want to overdose. How about other vitamins and minerals, such as iron, B12 and folate?

And PLEASE steer clear of iodine and seaweed products, unless and until you know if you are deficient. As said it is very unlikely

darkknightlt profile image
darkknightlt in reply to

Thank you, I will go and research how to test for it. The googling I did basically led to the same conclusion that certain minerals and trace elements are needed for conversion reaction. It makes sense to test if I lack those and then be guided by a practitioner and the results.

danym profile image
danym in reply to darkknightlt

let me know if you find something that works. I lost 30 pounds after my gallbladder surgery and with a gastritis and reflux flare and after this it seems that my numbers were all over the place, high ft4 1.8 from 1.2, low ft3 2.6 from 2.9, tsh increased to 1.4 from 0.4 when I decreased the dose of tirosint from 100 to 75, I still felt like the 75 was not enough but somehow was getting very hyper symptoms when trying to increase the dose jittery, heart alps, panicky, could not sleep :(

Just don't trust all you read on the internet

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