HI what is the Ft3 to ft4 ratio please my ft4 is 20 little high and my ft3 is 3.6 a little low of normal what's a healthy ratio. My endo says I'm converting fine but before my thyroidectomy my ft3 was higher than what it is now. .any advice please
Ft3 to ft4 ratio: HI what is the Ft3 to ft4 ratio... - Thyroid UK
Ft3 to ft4 ratio
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carroll998
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I don't like fT3 / fT4 ratios because the ratio is supposed to change as hormone levels change. In healthy people fT4 varies somewhat and the body maintains fT3 levels vaguely around mid-interval. So with lower fT4 the fT3 / fT4 ratio is highish and with a higher fT4 the ratio is lowish. When hormone levels are high type-1 deiodinase (D1) takes over and fT3 then gets higher but D1 also produces reverse T3, this seems to be a mechanism to reduce the effects of hyperthyroidism. So the ratio is not any use.
The best you can say is that fT3 should be around mid-interval. If you are on levothyroxine therapy fT4 may need to be around the upper quartile to achieve this.
Hi my ft4 is on the higher level bordering hyper but my ft3 is always at the lower end of normal. ..is this how it should be ??
Probably not, it would depend on where it is when you are not taking thyroid hormone.
Hi I take it on its own at 3 am every day 😊
Probably not. Most people would feel quite bad with those results and it would indicate poor conversion.
diogenesRemembering
I do like the fT3/fT4 ratio, because it gives on average how well you are converting T4 to T3. This ratio for you is 5.55/1. In health the average is about 3-3.5/1. For a good enough converter, on therapy (T4 only) the ratio shouldn't rise above 4.5/1. Yours is much higher than that. I suspect poor conversion and this would be confirmed by an rT3 measurement, which should show that the T4 is being converted to that rather than T3.
Hi what's an rt3 measurements entail please. ..please keep simple ...can you simplify what u said about ft3 and ft4 ratios please. ..I'm seeing my endo and he said I'm converting fine..I need to know what I'm talking about 😊
Dividing the FT4 value by the FT3 value is a rough measure of conversion of T4 to T3. The bigger the number, the poorer the conversion. 3 to 3.5/1 is normal for health, 3.5 to 4.5 in T4 therapy for adequate conversion (accompanied of course by well in range FT4 and FT3 values) and above 4.5 indicates inferior conversion. That is what you have (5.55) regardless of what the endo said. When poor converters are loaded with T4, the body cannot convert adequately to T3 which is what you need for health. This explains your low in range FT3. So another mechanism comes into play, producing a relative of T3 called rT3 which is not active. This is to get rid harmlessly of the extra T4 you can't use.
My dislike of an fT4 / fT3 ratio is because patients might take it as a single variable that is definitive. diogenes cautions '(accompanied of course by well in range FT4 and FT3 values)' which is fine. The fT4 / fT3 ratio varies as fT4 varies. Take a look at slide 18 in this powerpoint presentation acponline.org/system/files/... . fT3 tends to stay mid-interval whilst fT4 moves around within its interval - thus varying the ratio. I can give an example from some of my blood tests from when I experimented by coming off all hormone tablets and then gradually introducing levothyroxine only fT4 (12.0 - 22.0), fT3 (3.1 - 6.8): -
L-T4 000 ... fT4 13.0 ... fT3 4.4 ... Ratio 2.95
L-T4 050 ... fT4 15.5 ... fT3 4.1 ... Ratio 3.78
L-T4 100 ... fT4 18.3 ... fT3 3.6 ... Ratio 5.08
L-T4 125 ... fT4 24.0 ... fT3 5.5 ... Ratio 4.36
I was hypo on 0 L-T4, I was well on 100 mcg L-T4 physically but had poor cognition, I needed L-T3 to restore brain function. The increase from 100 to 125 made no difference clinically.
As you can see when my fT4 was 13 my fT4 / fT3 ratio was brilliant - it wasn't though because my fT3 was too low. The 50 mcg figures look great, ratio under 4.5 but the 100mcg ratio is not good at 5.08, notwithstanding I was better on the 100 mcg dose. The 125 mcg dose looks fantastic but it didn't do anything for me, perhaps because type-1 deiodinase (T4 -> T3 and T4 -> rT3) had taken over.
The fT4 / fT3 ratio can be very misleading, especially when it is quoted in an assay report. It depends what your fT4 is when you measure the ratio. I think it is much better to look at fT3 when fT4 is around mid-interval. If fT3 is low normal it is likely there is a conversion problem.
carroll998 Sorry for the technical digression! Your fT3 is similar to mine when my fT4 was 18.3. I need to take liothyronine. It is quite likley that you need it also, that your conversion is not working very well at the moment. Hypothyroidism guidelines usually suggest that fT4 is kept close to the upper quartile (where yours is) and that this will bring fT3 to mid-interval. This is not happening in your case. Levothyroxine only therapy reduces conversion a little as does removing a thyroid (research by deiogenes and his research team). An unusually low TSH (for fT3, fT4) can also lead to reduced conversion. Whatever the cause your conversion is below normal and you are most likely to need some liothyronine, probably around 20 to 40 mcg based on my experience.
Thank you so much for your advice, hopefully he'll listen a little more, I must keep calm 😊
I'm talking about ratios in more stable therapy conditions, not during change in dosing which can lead to all sorts of transient artefacts. Also ratios are most informative on T4 mono therapy, and not combined therapy where of course the ratio depends strictly on dosage and less on conversion.
These results were on levothyroxine only and over a period of I think up to six months (some time ago). I will be knocking up a document on this issue later this year which will explain much more, so will leave it for now as I've digressed too much from the original post.
Hi my latest bloods post op with ranges, I've also added blood test results pre op 2016...here goes
MARCH 2019:
TSH 0.2 RANGE 0.3 -5.5
FT3 3.8 RANGE 3.5 - 6.7
FT4 20.0 RANGE 10.0 - 19.80
PRE OP 2016:
FT4 17.9
TSH 0.1
FT3 5.7
thanks 😊
It looks like your fT3 is too low, probably because your pituitary is putting out too little TSH although it is difficult to judge when your fT4 is high. Do you have results when your fT4 was nearer the middle of its reference interval?
Hi these bloods were taken oct 2018
Tsh 0.7....in range
Ft3 2.9...below range
Ft4 14....in range
What do u think ?
If you look at screen 18 in the link I gave earlier you will see that in primary hypothyroidism TSH is very high when fT3 is low. In your case TSH is below average and your fT3 is low. Clearly your pituitary is failing to produce sufficient TSH for your fT3, fT4 levels. This is probably because you were hyperthyroid for some time. This can cause your “hypothalamic pituitary thyroid axis” to be down-regulated. An abnormally low TSH reduces T4 to T3 conversion (TSH promotes deiodinase). You need liothyronine to restore your fT3 levels. Furthermore you will need fT3 levels a little above average to provide enough T3 for your brain. The brain usually relies on type-2 deiodinase which is stimulated ty TSH. Too little TSH, too little T3 in the brain.
Hi and thank you. 1 last question what % should the ft4 and ft3 be and tsh if all normal and what % are mine at the moment ...I need to be able to know what I'm talking about to Endo. When people say in regard to ft4 75% or 9% ft3 I dont understand 75% or 9% of what. If normal what should the % be ?..sorry I'm a pain...sweet dreams
Hi you also said my Ft4 is low it isnt the tsh is and ft3 is ?
I’m confused! fT4 14 = just below average. fT3 2.9 = low. TSH 0.7 = very low for your combined fT3, fT4. Would expect TSH to be above 5.
My tsh never been 5. When I was normal my tsh always borderline
Do you mean normal before you were hyper? If so do you have blood test results from then?
Yes, my tsh been alway no more than 0.3 to 0.5 before op but because I was classed as normal thet didn't do t4 or t3 that was pre op, been suffer ing with my thyroid for years, they only removed because I had a substernal goitre. Before that had a parathyroidoctomy shame they didn't do it then he must have seen the goitre
I don’ like these percent figures, they give a false impression of precision. In healthy people TSH is around 1 or 2 and fT3 and fT4 vary around the middle of their reference intervals. For patients on levothyroxine only therapy the consensus is that fT4 will be around the upper quartile which brings fT3 to the middle of its reference interval. In this case the patients would have a lower TSH, probably below 1.0 but not suppressed.
I would emphasise that these are typical results that work for many patients with straightforward primary hypothyroidism (meaning their thyroid is failing). Many patients need different levels for complex reasons, it’s more important to pay attention to signs and symptoms that blood tests.
I’m a patient not a doctor.
Yes, but you are more informed than I, and I need all the help I can ger so when I see my endo I can sound a little knowledgeable. When I saw him last and asked for t3 he said I was converting fine because of my low tsh thars the reason my ft3 was low. I just need to know what I'm talking about to argue my case for t3. Thank you
But I haven't a thyroid to fail
Yes, it's worse without a thyroid because the thyroid contributes to peripheral T4 to T3 conversion. Your endo has got it wrong, your fT3 is low because your TSH is inappropriately low. Your TSH should be higher and that's why your fT3 is too low. To be honest I don't hold out much hope of an endocrinologist grasping that, most are pretty useless. You just have to be relentless and push hard. Take someone with you for support.
Unfortunately I'm on my own, both my daughters on holiday. I have had to f8ght with consultants quite alot over the last 10 years, sometimes you loose your energy to fight. To be fair my endo says because my tsh is low my ft3 is low. Even tho my tsh isca little higher now ft3 is low and t4 high. How do you solve this ?
You solve it by being prescribed liothyronine. It is sometimes possible to restore TSH function by giving TRH but this is not a standard treatment, I don't see your endocrinologist being good enough to do this or even understand it.
Any ideas if hr says no again, apart from going private?
When I return later can we do a senario where I ask you questions as though you are my endo consultant and where I struggle with answers/questions you can help. I'm sorry I'm asking so much but my meeting with Endo next Monday us so important to me. Its upto u. Either way you've been very helpful.
I think it's getting too complicated and we're going around in circles to some extent. If you try to plan in detail you will forget lots, I've been in your situation and I know how my memory would pack in under stress. I suggest you keep it simple, point out that as your endo said your fT3 is low because your TSH is low. Since you can't do much about the TSH it makes sense to bring up the fT3 with a trial of liothyronine. Giving you more levothyroxine will push you towards type-1 deiodinase which increases reverse T3. I'd just dig your heals in for liothyronine, I don't think you will get anywhere with technical arguments, you'd need to be very confident and have a deep understanding of the science to win the technical debate, otherwise you will just antagonise the endo.
Hi but my endo will reduce tyroxine not increase it....that is what he will say. Then if he reduces it, it will increase the tsh which he blames for high t4 and low ft3. Thank you for all your help you've been brilliant x
In the most basic terms....if taking levo only then high FT4 and low FT3 point to poor conversion.
Low FT3 being the result of poor conversion of the available (high/remains unconverted) FT4.
It looks as if you do not adequately convert T4 to T3....I think your endo is wrong!
Introducing T3 or NDT changes this.
You can use the search box at the top of the page to source info on previous posts.
Thank you so much, I see him next Thursday, I will try again to convince him that I need T3, before my thyroidectomy and damage to my parathyroids my ft3 was in the middle of range therefore to have a low ft3 is not normal for me. Thank you for your patience 😊
Sorry I'm back, when I mentioned about t3 last time he said because my ft4 was high end of range was ok for ft3 to b at lower. The guy who I see is an Endo surgeon. The endo I would like to c lives in a different part of the country and my gp says no funding available, unless I go before a panel to go there. I'm trying to fight for me. I wish I could afford to go private and get a prescription for ft3. Have a nice day
If you give us the reference ranges, along with the results, for FT4 and FT3, we can work out the percentage through range that you are for each. Then they can be compared. If they were both in balance at, say 75% through range, you would know that your conversion is fine. If, say, your FT4 was 90% through range and your FT3 20% through range, then that would show poor conversion.
Ok thank you , when I return home I will post them...thank you x
Ok here goes my bloods post op and bloods 1 year pre op.
March 2019
Tsh 0.2 range 0.3 - 5.5
Ft3 3.8 range 3.5 - 6.7
Ft4 20.0 range 10.0 - 19.80
Pre op 2016
Ft4 17.9
Tsh 0.1
Ft3 5.7
You can see before I had my thyroid removed my ft3 was fine, should I take these pre op blood tests results with me ?
My endo says I'm converting fine but before my thyroidectomy my ft3 was higher than what it is now. .any advice please .
Some conversion takes place in the thyroid, but also in the liver, gut, skeletal muscle, brain, etc.
This study tells us the thyroid gland produces predominantly T4 and a small amount of T3.
ncbi.nlm.nih.gov/books/NBK2...
Very scientific for those of us not that way inclined but the important bit is here:
THYROID HORMONE METABOLISM IN HUMANS which tells us about 80% of T3 is produced in peripheral tissues.
So you have no thyroid gland so some production of T3 is lost because of that.
So for the peripheral conversion you need a healthy gut, liver, etc.
Your current results
Ft4 20.0 range 10.0 - 19.80 - your FT4 is over range at 102%
Ft3 3.8 range 3.5 - 6.7 - your FT3 is 9% through range
So you have a very high FT4 and a very low FT3 which shows very poor conversion of T4 to T3. Show the maths to the endo and ask him to explain how that illustrates good conversion, especially compared to your results pre-op. Tell him that you know that T4 is a storage hormone/pro hormone and that T3 is the active hormone that every cell in our bodies need, and you are sadly lacking in the active hormone currently so no wonder you feel unwell.
Prior to your thyroidectomy (assuming range is the same)
Ft4 17.9 range 10.0 - 19.80 - 81% through range
Ft3 5.7 range 3.5 - 6.7 - 69% through range
You could certainly take your pre-op results with you to point out the difference.
I would be asking for nutrient levels to be checked:
Vit D
B12
Folate
Ferritin
All these are important and need to be optimal (not just in range) for thyroid hormone to work properly.
I would also ask for gut function to be tested just in case you have a problem there that's preventing conversion.
Maybe a liver function test as well.
And maybe a trial of T3. If he agrees to this, let us know what is proposed because some endos don't have a clue how to dose with T3 nor how to read test results when taking combination Levo/T3, and some even set patients up to fail.
Good luck with your appointment, let us know how it goes.
Thank you so much for your advice I will write it down and take it with me, had all the other blood test after I requested them all are good apart from Ferritin which is always low and I'm on iron pills. Once again I cant thank u enough 😊
Just a comment on your fT3 before you had your thyroid removed. You were hyperthyroid and usually in hyperthyroidism a higher proportion of T3 is secreted by the thyroid. So, although you may or may not have been good at converting T4 to T3 this would have been masked by increased thyroidal T3 secretion. For comparison you would need your figures for TSH, fT3 and fT4 when you were perfectly well. And of course they don’t run these tests if you are well - perhaps they should.
A thyroid genetic test will show if you have a DIO2 polymorphism inherited from one or both parents.
I am DIO2/homozygous ie from both parents and my conversion is v poor as a consequence.
They should not argue with a genetic test....if all else fails!
Excess unconverted T4 can make you feel unwell ....but it is eventually converted to rT3 and eliminated from the body
I wish medics were properly educated in thyroid matters....
Sorry this is a rushed scrappy reply hope it makes sense.
Read much, learn lots and take control!
I no longer rely on medics!
Sorry makes no sense to me but thanks for trying 😊
Oh dear, sorry!
I'm afraid we all have our own ways of dealing with what are very individual thyroid conditions with very different needs.. unfortunately, as you know, there is no "one cure for all" solution.
I am both DIO2/homozygous and thyroid hormone resistance which may help explain why my reply made little sense!
Your conversion is poor and the addition of T3 seems the next logical step, convincing an ill-informed endo may be another matter.
Personally I would prepare a time-line for the endo and add all the verifiable reasons/ research you have for considering/requesting a T3 trial, but keep it as concise as possible,
You've already had some very good advice from members who are better informed than most medics.
Wishing you good health
DD
Bless you and thanks x
Hi, just a little info which could explain my thyroid issues, I was born in Lowca in Cumbria, back in the fifties there was a massive radiation leak at Sellafield I lived a few miles away, most of my family have thyroid issues.
Gosh I remember Sellafield, so sorry you were in the midst of it all. I know someone who was working close to the Chernobyl disaster, she developed a form of cancer but thankfully is in remission.
So many innocent victims....
Good luck with your endo
DD
diogenesRemembering
At the end of the day, resolution of your symptoms by whatever means is the aim. Not homing in on this or that number but using trial and error with whatever product (T4, T3 or mix or NDT or mix) you can get and slowly but steadily trying it out to get the best result. And remember what you decide on won't necessarily be correct for ever. Thyroid deficiency response can change with age and one can't simply sit back and expect everything to be fine for ever after.
I understand all you've said and I am trying to help myself and symptoms by Trying to get t3, problem is my Endo doesn't think I need it
Jump the hurdle and reach beyond that closed minded endo..
You are hitting your head against a brick wall and causing yourself added stress if the endo "in his wisdom" continues to say "No" to T3.
Leave him behind and follow the advice you have been offered here - you won't get better anywhere. I can vouch for that, without TUK I doubt that I would be able to function sufficiently to write this.
The first step is the hardest....
Take care
DD
Having read all of the above and if your endo is unable to help then in your position I would be inclined to self medicate...as many of us here do very successfully. I was 72 when I took that decision and wish I'd been able to do so decades ago!
Sometimes you just need to "hit the books" and take control. The bottom line is, "How do you feel?"
You will get no better advice and support than here at TUK but there is no quick fix (think headache/paracetamol).
Given time, patience and determination there is light at the end of the tunnel....you can do it.
Just don't accept poor treatment!
Hi I'm a pensioner now and haven't got alot of money to go private. I would take control if my finances would allow...just for a consultation it costs 250...then private prescription. ..if I could do it to improve my health I would. Have a nice day 😊
No, no, no.....I wasn't suggesting you throw money at private treatments or questioning your financial status
Neither, as you seem to think, was I suggesting that you take control of your finances ...instead, I was suggesting you take control of your thyroid treatment.
pennyannie has explained, above, that she too self medicates, it costs much less than the private treatment you assumed I was suggesting!
I thought my comments were perfectly clear so I'm sorry if you misunderstood what was my intention to help and encourage you to - as pennyannie suggests -"do it yourself". That was the only option I had left!
We are all here to help by exchanging our experiences because we have all had (often huge) challenges to face.
I'm sorry, I understand what you were trying to day now, think I must be a little sensitive at the moment. I appreciate all the advice u and others are and still giving me x
Hello there again Carroll
I am a single pensioner having had to resign from work at 58 because of Graves Disease and the RAI treatment I received to " kill off " my thyroid back in back 2005.
Why go " private " when you can do it yourself ?
I too do not have that sort of money initially, or more especially, long term, to maintain a private prescription indefinitely.
I was denied a trial of T3 by Nhs because my TSH was suppressed. ??
I had no stability on Levothyroxine, and no help or understanding of how ill I became some 5 years ago. About 3 years ago I found this site and started my learning curve.
I found the stress of challenging " the system " didn't help me, and in fact the whole situation exacerbated my symptoms making me more anxious, nervous and stressed.
I " learnt the lines " and rehearsed everything I would say at appointment, and when in the room faced with two students and an endocrinologist asking me to give a brief outline of why I was there - I simply broke down in tears and nothing went like I had planned.
As previously posted you have " lost " the natural T3 production your thyroid would have produced, so, why not just try to supplement the T3 yourself ?
I did this and it worked in the short term for me.
I have now moved onto taking Natural Desiccated Thyroid as this hormone supplement contains all the known supplements a thyroid produces, viz, T1,T2, T3, T4 and calcitonin.
I am happier on this thyroid replacement, am still finding my way, but through trying the options myself, I know now which I prefer.
I didn't choose to self medicate but was left with no option and I'm doing ok.
Arh bless you, how did you supplement t3 ? also where do you get it from. Ndt ..where do you get it from, how do you know how much to take ?.
Its awful sitting there in fromn someone and trying to get as much info as you can to argue your case and they still say no. Your right I am upsetting myself and getting anxious about my appointment with him next week. 😊
If you write another post headed up " looking for T3 and or NDT " or something like that, you should get some answers privately, we are not allowed to openly discuss this on the forum.
I think you need to read up on all the other posts relating to T3 and NDT so that you will feel confident in trying alternatives to solely Levothyroxine.
It can be a lonely road.
I've no support from my doctor and am having to rely on myself , this website and several other books and publications for my knowledge base.
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