Thyroid UK
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Corticosteroids and Conversion

I have been having problems of low t3 since the start of the therapy. FT4 seemed ok but T3 and FT3 were always low. TSH also low sometimes. Now, when I look back, it comes to me that my problems with the thyroid started at the same time as the first asthma attacks. I was put on a corticoseroid which I have been using since last year. Yesterday I read an article about the conversion problems;

" Euthyroid sick syndrome and/or medication effect. When the TSH level is low secondary to euthyroid sick syndrome or a drug, or both, the free T3 level is usually found to be also low, which may be solely related to a component of euthyroid sick syndrome or secondary to the drugs themselves, as drugs such as corticosteroids and amiodarone inhibit the conversion of T4 to T3"

Any idea??

6 Replies

Are you on any thyroid meds? It may be that a small dose of T3 might even out the balance. Worth asking your doctor.


Thankcts, rosetrees. That is exactly what I am doing, taking a small dose of T3. I will be on costeroid therapy for asthma for another 5 months so it will be interesting to see if, after the therapy, the conversion will be any better.

1 like

I'm having the same problem. An on-going low free T3. Have been on Armour, 1 grain which I split and take am and pm. Since being on Armour, my TSH has stayed below 1. This has been going on all year and the on-going low T3 seems to be responsible for me having high blood pressure, fatigue, etc....

Every time I try and increase the Armour, I feel worse. So I think it's my Adrenal glands trying to down-regulate things. You can't help your thyroid, until you fix the Adrenal fatigue. I've been trying to do that.

In the past, I was on hydrocortisone, for over a year. I'm afraid now my Adrenals got too use to that. There's a feedback loop that tells the adrenals to stop producing cortisol. I thought I was on a low enough dose of hydrocortisone, that my adrenals would recover and start working again.

I did go through more stress in my life and I'm afraid I need to go back on hydrocortisone. I don't think I can ever raise my Armour dose and get my free T3 up until I do that. So seems like you being on steroids wouldn't hurt, it's coming off them that's the problem.

Another thing is your Iron levels, especially ferritin. mine has been borderline, in the 50s and I'm working to get it up to the optimal 70-90 range for helping thyroid and adrenal function.

I have read about amiodarone inhibiting conversion. Are you on that?


I am on Alvesco (ciclesonide) for asthma. Everything is under control and I will get off it in a few months'time. The problems with low t3 started at the same time. I also have the problem with the leaky gut. I have read somewhere that low t3 could be the result of some underlying illness, inflamation or auto immunity which get in the way of conversion.. I am trying to find what exactly: maybe gut problems, maybe asthma and corticosteroids and maybe adrenal disfunction as you said.

I am on combo 40t4+6t3. I feel good but the latest results were a disappointment: high ft4 and low tsh and ft3. I was confused because when I was on t4 only of 50 mcg, my Ft3 was 4 (ref 3.1-6,7) and now it fell to 2.4. But I have no symptoms any more, at least except low temp in the morning.


You might find this interesting, but quite possibly not at all helpful!

Postepy Dermatol Alergol. 2014 May;31(2):59-64. doi: 10.5114/pdia.2014.40924. Epub 2014 Apr 22.

Switching from systemic steroids to ciclesonide restores the hypothalamic pituitary-adrenal axis.

Marczak J1, Ciebiada M2, Górski P1.



Thank you helvella for the link. Some interesting articles on the effects of corticosteroids on adrenals and thyroid. One more proof that we must be careful not only what we eat but also what kind of medicines we use.


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