Straightforward explanation of TSH > T4 > T3 and why not testing FT3 doesn't present a full picture of thyroid health.
Top 5 Reasons Doctors Fail To Diagnose Hypothyr... - Thyroid UK
Top 5 Reasons Doctors Fail To Diagnose Hypothyroidism
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Thanks for posting
Enjoyed reading that as it puts the points across very well! Sad though that the people looking after us (!) won't listen. Its shocking that there is so much information and testimonials around and yet we cannot overturn the damage that is being done. I wonder what the GMC would do if we all complained about our GP's. Mass use of statins is very worrying and the latest thing. If people were listened to and correctly treated the NHS would save a fortune and that's before they realise the drug companies are ripping them off.
Hi Clever of you to find it. What a pity there is no confirmation from any Endo`s, probably afraid of the GMC. It just puts what I have been fighting for over 50 years.It is worse now than ever.I am still telling docs that to do a thyroid test, unasked and without permission, is not only illegal but means the patients may/has taken the meds. I keep telling them Vets have known that for years, but brick wall!
Best wishes,
Jackie
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I agree that FT3 should have much more prominence in thyroid function testing - of course with the provisos in nonthyroidal illnesses. There is no single test that will produce adequate results in all circumstances. In 1984, I analysed the first FT3 test produced and found that T4-therapy patients were much better placed in the "reference range" when considered properly dosed, than for TSH or for FT4. Still have the old document somewhere. The trouble today is that the manufacturers' combined development incompetence has led to wildly inconsistent FT3 assays produced, with readings for a single blood sample that could differ by 60%! Added to the lack of requests for FT3 and (especially in the US) an almost complete lack of understanding of the test's value, the test is expensive and there is at the moment little momentum and pressure to get things sorted out. A Ph.D study is envisaged in Belgium and that as far as I know is all that is likely to happen without outside pressure. Strangely enough, diagnosis was much better done in the 1980's when TSH performance was limited as first generation, and FT4 and FT3 were at least in Europe and Japan done on all patients. BTW, free rT3 would be a better test accompanying FT3 but no such test exists, though it would be easy to make one.
What does rT3 bind to? The same proteins as T3? Does rT3 "compete" with T3 for these?
I always worry when I see the term "exquisitely sensitive" related to TSH tests. The ability of the test to pick up phenomenally small amounts of TSH does nothing whatsoever to make it a good test for screening or managing thyroid hormone dosing!
Rod
rT3 will behave much like T3 in its binding properties, but I believe a little less strongly. Taking the 3 transport proteins TBG, transthyretin and albumin, I think it binds less strongly (but still very significantly) to TBG, and fairly equivalently to the other two. Regarding competition: this is a complicated answer. First T3 binds only at 10% of the strength of T4 to TBG, and pretty equivalently to the other two, except that in albumin it doesn't bind largely to the same sites. In the average person, about 25-30% of the TBG binding sites are occupied by T4. So because it is a weaker binder, T3 binding to TBG is at the mercy (if you like to put it that way) of the proportional occupation of binding sites with T4. The more occupation of TBG sites by T4, the less there is available for T3. rT3 binding also depends on the same situation and also will compete with T3 (but not T4) for the empty sites not occupied by T3 itself. For the other two proteins, there is no effective competition for binding between T4,T3 and rT3 because the proportion of binding sites occupied in these proteins is only 1% or less, so there are plenty available (99%) for molecules to bind independently.
Just another snippet for the group. Given the inconsistent production of free T3 tests, I've learned the best one closest to proper calibration and performance is the Vitros ECi FT3 assay marketed by Ortho Clinical Diagnostics.
And I thought OCD stood for Obsessive-Compulsive Disorder.
This is them:
orthoclinical.com/en-gb/Pag...
Rod
Very good site. Every doctor should read it. Sad that they had to put this at the end:
"Disclaimer
Hypothyroid Mom LLC, including all associated social media, is for informational purposes only and should not be considered a substitute for consulting your physician regarding medical advice pertaining to your health......"
Back to square one!
Brilliant article that for me says it all.......Oh that we could print out a copy without all the comments on the bottom ...far too many and my printer would do those first.
I would willingly give that to my GP.
Hubby to the rescue......says he can do it for me on his PC. x