Free T3 getting lower: To make a long story short... - Thyroid UK

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Free T3 getting lower

Betty-Lou profile image

To make a long story short, I can’t take T4 at all. It turns into reverse T3. Over a period of several months I’ve been taking T3 only (cytomel). When I got to 75 mcg my free T3 was 3.5 (3.1-6.8). The doctor agreed that we could raise it a bit. After several weeks of taking 100 mcg of T3, my free T3 is 3.1. Any idea of why? My GP is referring me to an endocrinologist. On Thursday I am having my B12, vitamin D, iron etc. checked.

11 Replies


What make of Liothyronine are you taking? Do you take it with water one hour before, or two hours after, food and drink and 2 hours away from other medicines and supplements?

Betty-Lou profile image
Betty-Lou in reply to Clutter

I take cytomel. I take it 30 minutes before coffee. I take it hours away from supplements.

Clutter profile image
Clutter in reply to Betty-Lou


Take it at least an hour away from coffee. Coffee can reduce absorption by up to 40%.

Thanks so much. I didn’t know that.

shaws profile image
shawsAdministrator in reply to Betty-Lou

This is a link:

guysgrams profile image
guysgrams in reply to shaws

That just explains about levothyroxine and coffee not Liothyronine. Is there a correlation too?

helvella profile image
helvellaAdministrator in reply to guysgrams


I have never found any good quality information on what affects the absorption of liothyronine. Most of what I have seen simply assumes similarity to levothyroxine. That seems a reasonable starting place - until proper research is published - but could well be found to be very wrong.

Betty-Lou profile image
Betty-Lou in reply to guysgrams

I was wondering the same thing.

shaws profile image

It does sound mysterious that you aren't absorbing T3 into your receptor cells. As that's all the absorb i.e. T3. Do you take it on an empty stomach and not eat for about 1 hour afterwards.

SlowDragon profile image

if you watch 2nd episode of this series (free for next few hours) it says coffee can be a problem

Have you considered compounded T3? Perhaps you have issue with the fillers in Cytomel.

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