This opinion piece concludes rT3 measurement has little use in diagnosis
Opinion
Front. Endocrinol. | doi: 10.3389/fendo.2019.00856
Can reverse T3 assay be employed to guide T4 versus T4/T3 therapy in hypothyroidism?
Cristiane J. Gomes-Lima1*, Leonard Wartofsky1 and Kenneth D. Burman2
How bizarre, I was just this minute wondering about what the point of this test was on private results. My google search had lead me to this blog:
hormonesdemystified.com/eve...
Not sure these blogs would go down well in on here maybe, but I find it helpful to read widely!!
There are plenty here who already believe rT3 testing has little benefit. 
I have been trying to get a grip of it via Dr Tania Smith who was also saying it is of limited value but I have not managed to get my head around it all yet. I just ignored RT3 thinking all a tad mysterious and that it must be part of the mechanism to protect the body/tissues from getting too much T3 like a safety valve/fine tuning which I think is sort of on the right lines but these shifting set points and dioadinases are doing my head in with it....
I think it probably is - but there are many reasons why the system thinks it needs less T3
I don’t know whether you have come across these hormones demystified blogs - written by an endocrinologist? There is so much confusion on the Internet I was drawn to the statement ‘separating endocrinology from quackery’.....
However, I'm not sure how much I trust the opinion of someone who wheels out the old "T3 is a stimulant, so it's like taking crack" argument. I can't really say categorically that this isn't true as I have never taken cocaine, but if I take T3 at night, it helps me sleep, so doesn't seem like much of a stimulant.
Frequently also applied to B12 (mainly, but not exclusively, applied to injections).
They probably say or write that just as they sip on their tea or coffee...
(Improved sleep was one of the first things I noticed on levothyroxine so am not at all surprised, or even questioning, that it can happen with T3 as well.)
Well T3 in NDT made me feel better but certainly not as high as a kite - Prozac is the one for that very “we have blast off” and happily dished out by GP’s in my experience and so inappropriately. It’s hipocratic hipocracy
I have no idea about that. Sure it’s written by a doctor so will be a completely different perspective to on here.
Yes, the man who writes HD has a totally different perspective to many people who read this forum. For example :
hormonesdemystified.com/top...
How many people on here would willingly stop buying their own tests? I certainly wouldn't.
When I go to see a doctor I am fobbed off, told I'm mentally ill and am just imagining things, and I'm more or less told to piss off. I leave the doctor's surgery with the same problems I arrived with and go home actually worse off than before because I'm angry, feel belittled, and am depressed.
The HD writer would approve of all of this I suspect, because I came to the conclusion when I found his website some time ago that he was an arrogant misogynist.
I get where you’re coming from... I have also paid for my own tests... though more out of curiosity than despair, so perhaps not coming from the same place as many on here. I have only read a select few of those blogs. I didn’t post it with any intent other than I had just read it. I also find the amount of conflicting info online completely overwhelming in the area of endocrinology!!
I think this paragraph sums his position up:
The mighty TSH test has already fallen. Taking a blood test and reporting its values to a patient and not being curious about their continued symptoms is not being a doctor. That’s just reading numbers… Patients have every right to order their own tests and investigate for ourselves. We paid doctors to do it, and they didn’t.
He condemns this outlook as bogus. What part of it does he think bogus; all of it or part of it, we don't know. From my perspective, the only thing I might agree with is to be careful if you are self medicating, and don't fall for quack ideas eg nutrition is all.
"The mighty TSH test has fallen." It certainly has as regards control of treatment.
"Taking a blood test and reporting its values to a patient and not being curious about their continued symptoms is not being a doctor. That’s just reading numbers".
But that is what too many endocrinologists/GPs seem to do. Numbers before presentation.
Patients have every right to order their own tests and investigate for ourselves. We paid doctors to do it, and they didn’t.
With careful self-understanding I wouldn't worry, but ideally doctor and patient should work together. However if they can't there's no possibility other than either being ill or taking the bull by the horns.
I think this fellow is out of touch, overly selfconfident that he knows everything (but doesn't say exactly what that is except "he knows best".
I sort of warmed to him (or her) a bit more after reading this one....! hormonesdemystified.com/you...
Link to article:
frontiersin.org/articles/10...
Are they really seriously claiming fad diets explain why we still feel ill on T4 monotherapy despite being “euthyroid”? Or is sick thyroid syndrome something else?
“The rationale for a need for combined T4/T3 therapy is based in large part on the discovery of polymorphisms in the deiodinase genes resulting in altered set points of feedback regulation of TSH”
but not because so many people on T4 monotherapy still feel ill! They do mention thIs earlier on, to be fair.
They claim because FT3 assays are so inaccurate free T3 is a worthless measure of thyroid healthy.
Sounds like hocus pocus to me. Is there any validity in this claim and their assertion that total T3 is a superior measure? I note there is zero questioning of the value or validity of TSH testing.
Is their opinion of any value? May be the RT3 part is right - I have yet to get my head around RT3.
My interpretation of sick euthyroid syndrome was that thyroid blood tests can be abnormal in the listed conditions eg. Critical illnesses, chronic inflammation, heart problems, starvation etc without meaning the person is hypothyroid. I somehow gleaned the idea from somewhere this could be a physiological mechanism to help stop them losing weight etc through illness by slowing the metabolism? If I am wrong please don’t hesitate to correct me!!! Actually it does mention in the article it is to ‘save energy and protein’.
Could be as you say and the article seemed to imply that it is something completely different to abnormal results on T4 monotherapy and persistent symptoms.
Reading it one might think a thyroid glad was not really needed for life given T4 toT3 conversion appears to be a minor occurrence in the gland compared to elsewhere in the body! I don’t buy that either.
I think it’s just all extremely complex!! If you have other serious illness then then the conversion of thyroid hormones may be influenced by that illness and needs to be considered in the overall picture. If you only have hypothyroidism and no other serious illness, then I don’t think euthyroid sick syndrome is of relevance (?)
It deffo is complex and it appears to me many supposed experts simply don’t understand it and have rigidly imposed an incorrect model to guide their practice that is seriously impacting on the people with the real problems of thyroid disorder and it poor treatment. Instead of getting us back to good health they keep us ill based on their ignorance, faulty reasoning and stubbornness to open their minds to new, illuminating research.
Authors seem to imply that there is no such thing as central hypo either as they appear to state that low but in range thyroid hormones with low or normal TSH are a) fine or b) caused by fad diets or NTIS - so apparently there is never anything wrong with the pituitary or hypothalamus
My interpretation was that they were describing the blood result picture in people who are not clinically hypothyroid, but ill and their body’s are adapting to try and preserve their weight and slow the metabolism to do this. This is different to central hypothyroidism, in which people would be clinically hypothyroid. So you can’t look at results alone and not a person.
Well, the article seems to suggest that central hypo is NOT clinically hypo as TSH is usually in range, free t3 is inaccurate (so should be ignored) and often free T4 is at bottom of normal range or only just below.
I think the thyroid blood results of the two different situations could be the same, but the condition of the person (and cause) would be completely different. I suppose with central hypo, most likely to be a pituitary problem, for example, will be diagnosed by abnormal pituitary function not just the thyroid tests alone.
But pituitary function is almost never tested and with opinions like this article, you can see why. BTW I have central hypo. And, of course, as with thyroid, if you are one point into the normal range, there is nothing wrong with you in spite of symptoms. After reading this, you'd be told that you had NTI caused by a fad diet or even subclinical hyperthyroid, I suspect, and given no further testing. Luckily, I suppose, my low cortisol was spotted first and the NHS tends to care more about this (but not much) than thyroid.
I can understand your frustration then...X
onlinelibrary.wiley.com/doi...
I was looking at a the table in this... the one with the hexagons...outlining interpretation of results....
And how do we know that the free T3 assay is inaccurate? Is it more inaccurate than free T4 and if so, why? I appreciate that it is now very easy to measure small amounts of TSH, but surely TSH varies through the day just as much as free T3 does, so diurnal variation can't be the reason for saying that testing free T3 is inaccurate or the same would have to be said about TSH?
In one sense it is true that the quality of many FT3 assays leaves a lot to be desired. The Abbott one is poor, for one. The basic problem is that FT3 assays are used so rarely (and hardly at all in USA: they use total T3 usually in routine labs) that manufacturers have no financial incentive to improve these assays. There are some good ones, but the majority are rather poor.
Can you give a broad brush picture of how bad FT3 tests can be?
Possibly some illustrations of results?
And which ones are good? At least if we are paying for private testing, we can choose to use labs which run the better quality tests. (Though we would have to ask the testing companies which test they use.)
Siemens is OK but not perfect, Abbot is no good, Ortho Vitros ECi is the best but rarely encountered. Others vary between just OK and bad, ie I wouldn't recommend unless unavoidable.
So how do we know that? Is it because multiple tests on the same bloods using the same assay give different results, but don't when using a different assay, or what?
I have just heard back from The Doctors Laboratory (TDL) used for some of the tests people here pay for. They said:
These thyroid tests are analysed on the cobas immunoassay analyser using the ECLIA method.
Good? Bad? Average? (I believe Cobas is Roche.)
Fair enough and reliable enough - not perfect - will misdiagnose very rare pople with deficient levels of binding proteins in blood.
Misdiagnose in which direction? FT3 too low or too high?
Either way: Lots of binding proteins, too high. Little amount, too low.
Monitor My Health have also replied:
We use Roche for our testing which is carried out in our NHS lab exeterlaboratory.com/ where the Monitor My Health team is based.
Oh dear. I wonder which one Thriva uses. Perhaps we are better to do as they did in the past and just go on how we feel if we take NDT.
I suggest you could ask them.
Will do I was just fishing in case anyone here knew. I understand the NHS use them, mind you I am still trying to get a blood sample to send off to them 🙄
When I did one recently, I could get it started easily but it didn't want to continue flowing sufficiently. Lowering my arm, and raising my legs, helped. Imagine lying flat on a bed and leaving one arm hanging down to the floor. (Mind, I didn't use sense and lie on an actual bed. I tried to approximate that while sitting on a chair. )
I did everything recommended but it was hopeless just one tiny blob that immediately clotted and nothing more. Second effort I did some running plus 6 flights of stairs and the rest - different finger again in the exact spot they showed on the diagram...same result. I did accidentally get bleeding from my leg and even filled the phial but all the while it was clotting fast but they said in the bumph it was usually ok if this happened. I sent it off but it was not ok and I now have a new test which they kindly provided gratis. I think only my veins will provide what’s needed. I assume my vit K must be adequate tho! It is now getting a venous draw done early enough, with no hols left till Jan and a 6am - 6:30pm working day with commute....
FOI - so much for Freedom Of Information. Article performing a clinical trial using T3-sulphate instead of T3 alone in a combination T4/T3 setting
New NHS Endocrinologist tomorrow for ‘Second Opinion’. Help with bloods please!
Direct measurement of T3 likely vital say researchersMathematical paper showing that TSH-controlled T4-T3 conversion inside the thyroid is responsible for circadian rhythm of FT3 lagging TSH
