Don't understand why my T4 keeps going down on same dose and my T3 is still high despite reducing the dose...

[Zazbag]

Hello,

Please could someone shed some light on my recent blood tests? I take 150mcg levothyroxine and 17.5mcg liothyronine. Vitamins are all optimal.

T4 decreasing despite same dose:

I've been on 150mcg levo since around October last year. I haven't varied the dose, brand or time of day I have taken it, but there has been a continuous decrease in my FT4 since then:

14th Jan: 21.4 (12 – 22)

4th Feb: 18.2 (12 – 22)

17th Feb: 17.2 (12 – 22)

Before increasing my dose to 150mcg, I was on 125mcg and my FT4 was:

7th Oct: 16.5 (12–22)

As you can see, my FT4 on 150mcg is only 0.7 higher than it was on 125mcg back in October. I'm wondering whether the reason is that I am converting T4 to T3 more efficiently now (because the lio has increased my ability to absorb nutrients from food – my ferritin is the highest it's ever been by far). Does FT4 work like this? Or am I just becoming more hypo?

T3 high despite lowering dose:

Last year I started taking 25mcg liothyronine in September. I messed up the timing of taking my last 5mcg, it was about 16–18 hours before my first blood test after adding, but it came out as:

7th Oct: 6.8 (3.1–6.8)

I thought that I probably needed to lower my dose, but I felt well on 25mcg and had an exam coming up so didn't want to risk feeling brain foggy. I then retested at 25mcg in January and this time I remembered to take my last 5mcg of lio 12 hours before the blood test (all blood tests since this I have remembered to stick to this protocol):

14th Jan: 8.1 (3.1–6.8)

Then I lowered it to 22.5mcg which I felt caused some hypo symptoms for about a week (brain fog, excessive hunger, tiredness)

4th February: 6.8 (3.1–6.8)

I decided to lower my dose further to 17.5mcg:

17th Feb: 7.4 (3.1–6.8)

I've now lowered it to 15mcg but I'm finding it confusing that my FT3 is higher at 17.5mcg than it was on 22.5mcg. Is this a Hashimoto's swing? I'm using the same brand of liothyronine however on 25/22.5mcg I was chopping up 50mcg tablets whereas on 17.5/15 I've been chopping up the 5mcg I have.

Please could someone explain why both of these trends are happening and what I should do next...? I actually feel well despite these test results, but I'm aware that long term over-replacement can cause serious issues. Thanks in advance.

[tattybogle]

Nope i refer you to my previous 'it's all run by blue pixies' theory of thyroid metabolism.

Seriously though , on the fT4 front ... perhaps adding T3 = lower TSH= lower t4 production from your own thyroid ? and perhaps because TSH is such a sloth in reaction times its a slow building effect ?

But i do also like your theory of being able to turn more to T4 to T3 .

As for the T3 . look on the bright side , if it carries on like this and you still feel ok when you reduce it , you might end up only needing 5mcg which would be dead cheap.

Sorry to be flippant , hopefully the 'sensible ones ' will have something more helpful to add

x

[FancyPants54]

That's odd. It's good that you feel well though. On 20mcg T3 and 125 Levo I am currently feeling worse than ever. So tired. So utterly worn out.

[Blot]

You have to remember that the more liothyronine you take the less T4 is manufactured in the Thyroid gland. Look for the reduction in your TSH. If that is coming down your Thyroid is being stimulated less, to produce T4. If your TSH is still high, the pituitary gland is still pumping out TSH but to little effect. Once either one of these results are calculated then you can determine whether you need to reduce the liothyronine or the levothyroxine with your GPs help.

[Zazbag in reply to Blot]

Thanks for replying! My TSH has been 0.02 since I first started taking liothyronine in September last year. It hasn't changed. What does this mean?

[Blot]

It means that the pituitary gland is not actively stimulating the Thyroid with its hormone(Thyroid Stimulating Hormone) to produce T4. What is your T4 count? If you are feeling well it could be perfectly adequate for YOU.

[Zazbag in reply to Blot]

I've been on 150mcg levo since around October last year. I haven't varied the dose, brand or time of day I have taken it, but there has been a continuous decrease in my FT4 since then:

14th Jan: 21.4 (12 – 22)

4th Feb: 18.2 (12 – 22)

17th Feb: 17.2 (12 – 22)

Before increasing my dose to 150mcg, I was on 125mcg and my FT4 was:

7th Oct: 16.5 (12–22)

[Blot in reply to Zazbag]

Reduce your liothyronine. Your T4 levels are OK without it at the moment. If you are taking the T3 and T4 is it's precursor, no wonder your T4 is going down!! It isn't needed so much. After all, T4 converts to T3 and if you are over supplementing on T3, the TSH will switch off and the thyroid gland reduce the manufacture of T4

[Zazbag in reply to Blot]

So I can assume that my thyroid was producing about 21.4–17.2=4.2 of T4 but that has diminished now because my TSH is so suppressed? I'm taking 15mcg of liothyronine atm. I'm just don't want to reduce it by so much that I start feeling hypo again. When I went from 22.5mcg to 18.75mcg I felt really hypo that week and yesterday and today (about 4 days after reducing from 17.5mcg) I've felt quite tired and demotivated and a bit brain foggy.

[Blot in reply to Zazbag]

Not entirely correct.... it is diminishing perhaps because the T3 is already providing adequate amounts of the hormone.The TSH release is prompted when the level of T4 goes down below a certain level. It's too high at the moment to make that happen.

When the really warm weather comes you could try to reduce the liothronine to 10 especially if you start losing weight. But check it out with your medical adviser

[Blot in reply to Blot]

The level of the T4 is too high to make the TSH rise

[Blot]

I mean..... producing more T4.Mine is only7.8 mmvols. (not quite the correct abbreviation spelling!) and l can't take Levothyroxine and am quite OK with 10mcmg liothyronine. Mind you my TSH is about 16... a bit high and antibodies somewhat off the chart still.

If you are feeling well and health is a good marker., l would advise keeping an eye on your Folate status as ferritin levels do drop with hashimotos and we can become anaemic and mistake the Fatigue of anaemia with incorrect thyroxin doses. A good thyroid profile from time is helpful...... and keep copies of your results to mark what's going up or down

[Zazbag]

All my vitamins are optimal. I'm concerned about the downward trend. I tolerate levo fine and I take a high dose so I guess that's why my FT4 is higher than yours. It's not the only issue though, my T3 seems to be high even though I have reduced my dose of liothyronine. I feel like these two issues are probably connected.