Has selenium supplement helped t4 to t3 convers... - Thyroid UK

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Has selenium supplement helped t4 to t3 conversion?


Hi all, I have been taking 200 mcg selenium supplement four hours after 75 mcg sodium levothyroxine for a year. My last annual blood tests showed that my TSH 3.48 no test for T4. Doctor at that time said under 5 is normal. The current annual blood test now shows TSH 7, T4 is 17. Dr will increase current dosage 75 mcg to 100 mcg. Clearly in my case selenium has not helped and I take a good quality selenium supplement. I take Actavis brand for the levo. Should I continue to take selenium? Your comments much appreciated. Thank you.

7 Replies

Selenium is part of the T4-T3 converting enzyme and. does help better T4-T3 conversion especially in the elderly who are often short of this element. Link is:

Biol Trace Elem Res. 1996 Jan;51(1):31-41.

Selenium, zinc, and thyroid hormones in healthy subjects: low T3/T4 ratio in the elderly is related to impaired selenium status.

Olivieri O1, Girelli D, Stanzial AM, Rossi L, Bassi A, Corrocher R.


You were under medicated to have TSH 3.48. Increasing dose to 100mcg should raise FT4 and reduce TSH to optimal 0.30 - 1.0. It will be beneficial to continue taking selenium.


Have you ever had FT3 tested at the same time as FT4? That's the only way you'll know if you're converting T4 to T3 and whether it has improved over time after supplementing with selenium.

Clutter, thank you I will continue taking the selenium. Just got the print out of test results and apparently correct TSH is 7.67, T4 17, Also serum ferritin is 27. Vitamin D 94 and Cholesterol 5.4, Serum HDL Cholesterol level 1.6, Serum Cholesterol/HDL ratio 3.38

SeasideSusie, thank you, I have asked them many times before and today, they just do TSH and T4 tests only.

diogenes, thank you that is good to know. Knowing the correct amount of selenium to take on a daily basis is important as well without over dosing. Maybe I should take it at the same time as the sodium levothyroxine to help the conversion.


The trouble is, you have no way of knowing if your TSH might have reached 20 (or any other random number) had you not taken selenium!

It is extraordinarily difficult to know about the effects of anything on our systems unless we can cycle through using/not using several times and can thereby directly judge those effects (if any).

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