Thyroid UK
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Reasons for impaired conversion and lingering symptoms on levo alone

We talk a lot about conversion problems here. They can be easy to spot in blood tests: if you're on a good dose of levo and your tsh has responded but it looks like your t4 is backing up (high) and t3 is low.

When I see a post that says something like 'I'm still symptomatic on a good dose of levo' I often comment that the op may still benefit from the addition of some t3 despite having no conversion problem. I feel like I should have a rubber stamp made. :-)

My blood tests always showed good conversion, but despite what looked like an ideal t3 result (high in range) I was bloated, breathless, constipated, losing hair and exhausted. At the time I estimated that levo had given me a 20% improvement in my symptoms, which consisted of feeling slightly less sedated, slightly better feelings of desperation, not suffering w cold all the time.

A small addition of t3 made me feel loads better, and although I've had my ups and downs, a life w t3 is immeasurably better than a life on levo alone. My weight is more or less what it was before dx, my hair and brows have come back, I don't feel desperate or on the verge of tears all the time, I'm no longer breathless, gut situation is good (no more terrible constipation), etc.

I started to wonder why that is, why my tests looked good but I still felt awful on levo. There were so many concrete improvements after adding t3 that, although I'm open to the suggestion that it might be acting as a placebo, I didn't think that the sudden fluid loss and improvement in bowel function could be classed under the placebo effect. My mother also feels better on ndt (after being on levo for many years) so I imagined there could be some genetic reason we both need some t3 to relieve symptoms. So I found this article very interesting.

'The recent breakthrough discoveries described in the WATTS study reveal for the first time that individuals differ in how their bodies process (metabolize) thyroid hormone. While some may convert enough t4 to t3 in the cells of the body to restore normal function, due to genetic differences some individuals will not be able to make enough t3 leaving them with persistent hypothyroid symptoms. Since the problem is a deficiency of t3 within the cells of the body, measuring thyroid hormone levels in the blood cannot adequately reveal the problem. T4 replacement treatment alone can result in thyroid levels that appear normal on blood tests so doctors conclude that persistent hypothyroid symptoms are not related to the hormone therapy.'

32 Replies

eljii that's fascinating. So 24hr urine would be able to tell you whether or not you had enough cellular conversion/t3 (delete as necessary, I'm not 100% sure how you'd express it)?

Funny you should say that, when I underwent a battery of tests in my teens (around 1987) to try and find out why I was so depressed (it was an experimental and I think probably very lucrative trial at a local private rehab centre), I did have to drag a huge bottle around to collect urine for a whole day. I think it had some tablets in the bottom if I remember correctly. I always thought that was something to do w cortisol (maybe it was) - ? I had never heard of 24hr urine collection before.



Genova do the 24 hour urine test.

I did this when I was on 100mcg of levo. My G.P. had reduced it from 125mcg. to 100mcg.

The result showed I was actually converting the T4 into T3 quite well but I was just not taking enough of it to get rid of my symptoms. This was confirmed by the return of symptoms when reduced to 100mcg.

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So lucylocks that is v interesting as, at the moment all my blood results still look good but I feel like cr@p. After I posted this I had a lightbulb moment thinking even when I think I'm on enough meds (when my bloods are good), am I really? I feel very hypo, like properly miserable (worse since gp reduced my meds twice in the last two years, but my bloods were good in Feb, when I also didn't feel great). My tests have generally looked good (until my last lot, which looked v hypo). How do I know if that hormone is going where it should?

There is such a lag on my symptoms and they're so subtle that it has taken all this time to know I'm now on too little meds. In other words I can't just shift up my meds 25mcg and tell the difference.

What made you choose the 24hr urine test?



I was advised on another thyroid forum to have it done as I was still suffering symptoms. They explained that the blood tests show what thyroid hormones are in your blood but does not show what is getting into your cells. The urine test apparently shows if the T4 is converting into T3.

On my blood tests my TSH was always suppressed and T4 and T3 just mid range.

The link below is to the test at Genova, the only thing is that it has to be ordered through a private practitioner, but the other thyroid forum can act as one if you join, membership is free.

Let me know if you want to know the other forums name.


lucylocks and puncturedbicycle

You can get the Genova Thyroid Urine Test using ThyroidUK as your practioner.

Here is Genova's tests detail page on TUK

It also tells you how to receive your results.

If you click on Download A PDF... list of tests at the top it will give you the full list of tests they do. The thyroid urine test is END08 and costs £101. Here's the link if you're on a PC

I've done this test twice. Once when on Levo only, which confirmed what the blood test was telling me, that my conversion was poor. Second time was when I'd been on Levo/T3 combo for 3 months and the difference was quite amazing.

It's quite important, for accuracy of results, to make sure the tests lasts exactly 24 hours from the first discarded sample to the last collected sample, and that you take your normal thyroid meds only during that 24 hours even if it means adjusting the timing and delaying your meds the next day until after you've done your last sample.


Many thanks SeasideSusie.

I wasn't aware Thyroid UK could act as Practitioner, that really is good to know.

Thank you for letting us know.

Best wishes lucylocks.


Yes, you use the code on the page I linked to and it puts the name of the practioner on, not TUK itself but one of their advisors/trustees.


I have just had a look at the link and can see who the advisor is.

Many thanks again.


SeasideSusie and lucylocks, sorry to spam you w questions but does this mean I can take the t3/t4 combo and still they can tell from the 24hr urine test if I'm getting enough meds on a cellular level?

And you take your usual dose of meds during the 24hrs you're testing?

Sorry, will get on and read about it but it is always good to ask people who have already done it. :-)


Don't worry puncturedbicycle :)

The urine test takes a bit to get your head around. Some people don't think it's much use, well it isn't for diagnosis but it is a useful tool that can be used alongside blood tests and shows conversion very well as the results come as a graphic. My experience shows that it does tell you what is going on at cellular level which is different from what the blood test shows.

You can't compare them as they're measuring two different thngs. The blood test shows what's going on in your blood at a particular point in time (the free Ts). The urine test tells you what has been through your cells over a 24 hour period because it measures the breakdown products.

You need to take your meds because you are measuring the metabolites (breakdown products) so you need to see how the T4 and T3 have been used. It is important to only take the exact amount of meds you'd normally take in 24 hours. It's also important that the 24 hours of the test is strictly adhered to.

For example. Say you get up at 7am and urinate. Discard that urination but note that you did it at 7am. You then collect all urine throughout the next 24 hours, and you collect your last urine at 7am the next day.

For your meds, say if you normally take them at 7am for one dose of Levo, or 7am and 4pm for 2 doses of NDT or Levo/T3. Then when you get up for your first urination at 7am, you would take your dose after that urination. Then take any other meds as normal throughout that day. The next day, when you do your 7am urination, you delay your meds until after you've done it. Otherwise, there would be two days' meds within that 24 hour collection period.

You are advised how much liquid intake to limit yourself to during that 24 hour period (1.5 litres max), because you don't want to go over their recommended level. I suppose their machines are calibrated to do the maths with certain figures.

Hopefully this link will show a sample report

I find the graphics much easier than figures to understand with the urine test.

Ideally, for someone with good conversion, the T3 would be showing higher in it's range than the T4 is in it's range.

As an example, this is how my results were.

My first urine test showed T3 about 3/4 of the way into the lower red zone, so I was under range - T3 was -0.06% of range (yes minus) .

My T4 was about 1/3 of the way into the green zone - 39% through range.

This showed my conversion was poor which confirmed the same finding in a blood test which showed an over the top FT4 and barely mid-range FT3.

I lowered my Levo, added a bit of T3 and retested after 3 months. It then showed:

T3 getting on towards half way through range at 43%

T4 getting towards 1/3 through range at 29%.

I haven't retested since then, I need to get around to it.

I hope that's clear. I know I ramble on so hopefully you've been able to follow it. If not, just ask.


Wow, that was super helpful, you explained it brilliantly. I am the queen of rambling so don't worry about it, sometimes it allows you to get your point across better than trying to be succinct. :-)

I guess the $64m question is do you feel better after the adjustments you've made in your meds in reaction to the test results? And, if this is appropriate (as you have yet to do another follow-up test), how does it affect your bloods, as in, if I adjust my meds to the urine results instead of the bloods will it make my gp freak out?

I need to do something, I feel like ******* ****. (That's bad, btw.) I just want to avoid randomly throwing money at it.

So as usual, just when I'm thinking, Hmm, I spend entirely too much time here, I should do some chores, I discover some new helpful bit of info. :-)


That's hard to answer as there are other things going on that I am addressing at the same time (adrenals and sex hormones, plus I have a lung disease which has made me unwell for most of this year so it doesn't help).

My first urine test was last November when I was on Levo only (and feeling pretty carp). I then dropped my Levo by 25mcg and added 6.25mcg T3. I didn't find any difference but didn't want to rush things so I waited for about 3 weeks before I added a second dose of 6.25mcg T3. Still didn't have that 'Wow I feel better!' moment.

I then did a whole barrage of tests to try to get to the bottom of why I'd been feeling so unwell for so many years - all the sex hormones, adrenal test, candida, iodine, to rule in or out any problems. Cortisol was top of range for the first 3 samples, DHEA was bottom of and under range for those two samples. Sex hormones were virtually non-existent. So I'd had to consult a practioner for interpretation of those tests who suggested a supplement regime to address the problems.

Now, 9 months after first starting to add T3, and 6 months after starting the supplement regime, I can say I am in a better place. I still have some way to go.

I feel like I want to increase the T3 by another 6.25mcg but I am Cautious Cathy and want to see what my test results are like first.

I need to repeat the thyroid, adrenal and hormone tests to see what's happening but can't afford it at the moment as I'm paying to see a lung specialist privately. That's because the GP I see for that (the one with a special interest in lungs) wont treat my infections appropriately, causing more damage to my lungs, and is about as useless as the one who only goes by TSH tests and disregards FT4/FT3 and symptoms.

You asked

And, if this is appropriate (as you have yet to do another follow-up test), how does it affect your bloods, as in, if I adjust my meds to the urine results instead of the bloods will it make my gp freak out?

The way I'm looking at it is, it's generally thought that with blood tests it's important to keep the FT3 in range, which is what I would do. The urine test will always show the T4 and T3 lower in it's ranges than the results of the blood test (because they're measuring two different things and you can't compare). So I don't think hyou can really dose by urine test (as in aiming to get the levels within the top quarter or third like with the blood test) and disregard the blood test, but you can adjust your combination of T4/T3 if the results show you're T3 is lower than your T4.

Will you GP freak out? Quite possibly because they don't recognise urine tests. Not sure if an Endo would.

I think the Belgian doctors (Hertoghe?) use urine tests.

My GP has nothing to do with my T3 or my adrenals/sex hormones, they know nothing about it. There's no point, I'd get nowhere, so I do my own thing. I just take my prescription for Levo, self source the T3, dodge their requests for thyroid tests, test privately when I can. My GP wont 'discuss' my suppressed TSH but in range FT4/FT3 and is happy for me to be symptomatic and just tell me I'm overmedicated, so I wont discuss my thyroid with her either.

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With you on the rubber stamp. :)

I think the other thing to consider is *why* you might be a poor converter - it's often low ferritin. Selenium is also required and according to Dr Peter Osborne, so is Vit C and Vit B2 (not a typo - B2).


Yes of course, best to try to sort out any deficiencies.

For me the question was: why is adding t3 restoring health when I seemed to have so much of it already on levo alone? So my t3 results didn't reflect how I felt on levo, or how much better I felt adding in some t3.

I felt like a fraud (or suggestible) because taking the pill made me feel better even though there was already t3 aplenty. So I'm trying to figure out what accounts for that.

In the meantime people spend so much time feeling awful and thinking the test results don't lie etc when they could shortcut all the nonsense w a t3 trial. If my doctor hadn't suggested I try some t3 I don't know where I'd be now.

I'm off to have that rubber stamp made. :-)

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If you find a cheap stamp maker, let me know. :)

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I'm the same. Big improvement when T3 added. I was worried this week when the pharmacist told me they had stopped making it. There was only one supplier. They couldn't get it so I went to a different pharmacist who had some. Hope to goodness this isn't right and that we will be able to get it.


Blimey, they'll have to pry it from my cold dead hands.

Summer64 was your conversion meant to be ok before you started taking t3?


No it wasn't. They found I couldn't absorb some nutrients like Vitamin D either.


The distinction I'm making in this post is that my conversion looked fine, which is why I couldn't figure out why I felt so rubbish. At least if your conversion is obviously not good you have some results to show for it. I just felt like a fraud. :-)

Like you I have trouble w d and my b12 was falling like a stone as soon as I stopped supplementing, so I self-inject now.


The problem I have now is getting any tests done as the endo sent a letter to my gp years ago now advising testing every 6 months and for a while that happened. Now that letter has been conveniently lost and I went 3 years without any testing as they say they don't do it. I get an annual TSH but that's all


No way to get in contact w the endo and ask for a copy to be sent? I guess this is a good warning for the rest of us to get and keep copies of such things, which wouldn't otherwise have occurred to me.

Can you find a new gp? It's nonsense that they can't test it, esp if you're actually taking it.


I suppose I could try that. At least I did get one this year. I did change GP's, not that I wanted to, we just had a new one come about 5 years ago and some of us were automatically moved onto his list.


You may know this already, but if you're taking t3 they must write it on the bloods form. It seems to be the only way I get it done these days. If they just tick the box on the form the lab refuses it.

So if you manage to get a gp to request it, just ensure that's done. (Then if you're me you'll ask every person from the receptionist to the phlebotomist to the traffic warden to the window cleaner if they have the right form and the right vials and if it is *written in ink on the form* and make them write it a thousand times on the blackboard. It's the only way.)


Thanks. I am due a blood test next month for thyroid so I'll see what is on the form.


There's only one official supplier to the NHS, that is true. A supplier who charges way way way over the odds for the stuff, even though it costs a couple of pounds a packet in other parts of Europe.

But there are other brands.

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Even in the US it is much much cheaper (about $100 for three months of 10mcg tablets).


Hi puncturedbicycle would you mind pm'ing me the details of where I can but T3?

I would like to have some to try for after when I've had my next thyroid blood tests.

Many thanks



Lulu_65 I'm afraid mine is prescribed and my old source of online t3 has dried up. If you do a post people who buy online will certainly pm you. :-)


PS. I often wonder when they'll stop prescribing it. I'll be looking for an online source before long.


How much on the reference range was your Free t3 before and after adding T3 to your regime?

Also, how much T4 are you taking and how many times a day and for how much are you taking T3?

Thank you.


Was that for me? If so, on levo alone my t3 and t4 results were both high in range and tsh low, possibly below range. I'm afraid I don't have the results in front of me as that was a few years ago, but I saw the numbers myself and was satisfied it was as it should be.

Before t3 (levo alone) I was on 150 levo. After t3 I was on 150 levo + 10 t3. Then I went a little over and had a crash, then levo was reduced little by little until I was on the lowest dose of 50. All my tests showed low/suppressed tsh and t3 high in range, until last results which showed high tsh (5ish) and I think t3 was ok but t4 low in range.

The only significant difference after adding t3 is that the t4 is lower in range which is to be expected. When I had my first test after adding t3 my t3 went slightly over range but that doctor had wanted me to keep my levo at 150 as it then was, so it was not unexpected that I went over a bit.

Right now I'm on 100 levo (recently raised from 75) and 10 t3, both of which I take at 8:30am, which for me is more than an hour before I get up and have breakfast.


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