I can never be confident that I know what my conversion is like so if someone tells me how to do it with fresh blood results for FT4 and FT3, I will ask my husband if he can add a line to the Dopiaza thyroid calculator for us. It would be a useful addition I think.
I've seen the calculations in the past but can't remember them.
No idea how to do it myself but this page has fields to fill in and calculate
I "think" that's a different thing. That's a ratio. I want to know my conversion rate, which again I "think" might be different to that?
But you have made me realise that if the Ratio is the conversion rate, I need to ask for info to enter into the calculator for what a good, bad or indifferent ratio might be for patients.
Ooooo, I don't know. Above my understanding I think. 😁
FP54,
Maybe look at this thread. ... healthunlocked.com/thyroidu...
The overall message of that thread seems to be that conversion is very volatile and not really worth worrying about?
Oh, I see what you mean now FP .... how to work out the ratio to enable assessment of conversion abilities.
Some people divide FT3 by FT4 and using this method a higher result is deemed to be better.
Other people divide FT4 by FT3 and using this method a lower result is deemed to be better.
The 'best' ratios will change determined by the meds you're taking, eg T4 only or a combo, and be careful to use ratio guides of those medicating and not healthy subjects (non-medicated).
And time is critical.
If you take a levothyroxine tablet and get tested two hours later, the ratio will be skewed to T4.
The peak of T3 that is attributable to a dose of levothyroxine occurs about 48 hours after ingestion.
But the actual blood T3 level will be a balance between additions to the T3 by conversion, any T3 taken, and the T3 taken in by cells everywhere - and presumably converted to T2, etc.
Our bodies seem to attempt to stabilise T3 levels over pretty much everything else.
And also that T3 made within the thyroid gland (for those who have any remaining).
We would hope the used results to obtain the ratio be taken from labs performed according to forum protocols, eg the same timings.
I'm not a huge fan of using ratios to gauge conversion as the resulting number is too precise when the many variables will change it from hour to hour. However, I think it very useful as a med dosing guide.
I don't understand what you mean by useful as a med dosing guide?
Comparing FT4 levels to FT3 to see if T3 meds need introducing or doses titivating.
Mine certainly works hard to keep my T3 level and low!
Out of curiosity, I googled it, so thought I’d paste what I found. On the surface it’s logical but I have no experience using the info. I see the lively debate a week ago in the other thread so just sharing what I’ve read.
The equation is: ft3/ft4 ie, ft3 over ft4
optimaldx.com/calculators/f...
The link says:
This ratio helps in understanding how effectively T4 is being converted to the more active T3 hormone, which is crucial for regulating metabolism, energy levels, and overall bodily functions.
That website says the range is:
Range: 2.4 – 2.7 Ratio (FT3 in pg/mL and FT4 in ng/dL)
It looks like mixing units is usual, as I read somewhere else that if using pg/mL for FT3 and ng/dL for FT4, the normal range is ~0.31–0.50.
But if using pmol/L for both FT3 and FT4, the normal range is ~3.2–4.2.
I also see it written as ft3/ft4 x 100 to get a percent. Whereas under 30% is good and over 30% suggests over conversion or t3 pooling.
Caveat- this is just a summary of some articles nit sure how perfect they are.
Using masses (weights) such as nanograms or picograms has the perception distorting effect that if 100 micrograms of T4 were completely converted to T3, you'd only end up with 83.793 micrograms of T3.
I think most of us feel that the scale of conversion should go from zero to 100%. Not zero to 83.793%.
Using molar quantities addresses that.
Interestingly, to some of us people with odd minds, a 25 microgram T4 tablet has very close to the same number of molecules of T4 as a 20 microgram T3 tablet has of T3.
See the reply from diogenes, here: healthunlocked.com/thyroidu...
I posted Paul Robinson's formula here awhile back:
Divide your FT3 by your FT4. Good conversion would be 0.26 or above. Under 0.22 means poor conversion. Under 0.22 means your not getting enough T3 into your cells from Levothyroxine allone. I've been under-medicated for 15 years and I still am!
Why are you still under medicated if you know about it?
Does trying to raise your dose cause you problems?
I'm a bad converter. I've tried to get T3 added for years but without success, I finally gave up trying.
That's terrible. I'm so sorry. I buy T3, at the moment in the form of Armour NDT. But even then my FT3 seems to stay low and raising the dose has made me feel worse in the past.
The problem I have, aside from the cost, is figuring out how much T3 or combination of T3 and T4, to take. My GP surgery refused to help with it when I asked as it wouldn't be a prescribed medication.
helvella Do you agree with Paul's suggestion of how to work it out above and his assessment of 0.22 and under means poor conversion? That's a simple calculation we could add to the calculator page. But is there any point in adding it at all? What would this tell the layperson that they could improve? Could the extra data just confuse more and upset some?
I think it is simplistic to take such a formula and assume it applies to everyone.
It might suggest a direction but I'd be very wary of any cut-off.
There are so many things that could throw it off.
Well, I got the formula from Paul Robinson in an email to me and applied it to my blood results (at that time) and it showed me to a bad converter of T4 (in fact I have Hashimoto's).
It might well work for some people, some of the time.
But there is a bit of a problem with I am a poor converter because this formula says I am a poor converter!
Well take it up with Paul Robinson, he seems to have a very thorough understanding of the issues. And when I applied to my own results, it worked. I am a poor converter and my symptoms confirm it.
Interesting. What does your doctor say about the result you got from Paul Robinsons formula?
I never raised it, I've yet to come across a GP, in the 15 years since I was diagnosed with an underactive thyroid, who has a clue about the condition. They either regurgitate the standard NHS response or admit their complete ignorance and in all that time, I've seen one endoctrinologist who was also clueless and another, who in an email told me that if I was coming to see him to get prescribed T3, to forget it! I never bothered to go. For me, T4 reduces the symptoms of hypothyroidism but I have a range of them including feeling cold when the temp drops below 23C, messed up digestion and low energy levels, dry skin, brittle nails and hair, bad skin on my back.
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