I wanted to get opinion on this email I received when I emailed a query about Total T4/Total T3 blood tests through my hospitals link "FOI" as not listed in there pathology listing...
This is a copy of the email.
Dear Mrs Edmunds
Thank you for your enquiry which was passed on to me.
We don't measure total T4 and total T3 any longer because most of the T4 and T3 in the blood is carried around by a protein which inactivates them. It is a sort of storage form of T4 and T3.
A much smaller amount of the T4 and T3 in the blood is in the active or free state, and this is what we measure (Free T4 and Free T3).
I have checked up and I can't find any UK labs that still measure Total T4 and Total T3 - we all stopped about 25 years ago when the free hormone tests became available.
Best wishes
XXXXXXX XXXXXX
Consultant Chemical Pathologist
I spoke to my GP who is being extremely helpful and she agreed incorrect information, I know the last time I had Total's done was at least 12 years ago, but all the same, I was under the impression that FOI would only give you STATEMENT and not OPINION or completely made up information!
Maybe I have missed something here?
=]
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AddiFeelsCack
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They only had to tell you they don't do tT3 or tT4 assays.
They seem to have gone further and explained why and checked for labs that do these assays. They didn't need to do this, they were just being helpful. I don't see why you would want the total assays, you could get them done privately but they are unlikely to be of any clinical relevance. It's the free hormone that is relevant, primarily the fT4, the fT3 figure doesn't tell you how much free T3 is produced in the cells.
In general terms, I think the lab is right. But the possibility of doing total tests, in unusual cases, doesn't seem too much to hope for.
Nevertheless, I agree with Jim, I think they were being helpful. Nothing in the FOI seems to me to preclude putting some sort of context to their reply. What is it about their reply that seems to have upset you? What is completely made up? Or even an opinion?
The reason I feel this is not giving correct information is that to see if T4 is converting to T3, you need the total for reference when looking at the FT3, the way it reads seems to dismiss its relevance, also, as I said, I had totals last done about 12 years ago, and when I was first diagnosed over 20 years ago, every test at that time included TT4 and TT3. my current GP even agreed that totals are still being used in labs.
I am trying to get all the information in one handy little basket, so to speak, to know what is available to me either privately or through NHS. As they say, knowledge is power, but so often rules and regulations change, information is updated or outdated and it can be difficult to know what is accurate for where we live.
Thank you all kindly for your replies, especially the lab, onwards and upwards
Most conversion (deiodinase) is carried out within the cells by Type 2 Deiodinase. Only free T4 enters the cells, so the total T4 is of no use in determining conversion rates.
A serum fT3 assay will tell you how much fT3 you have in the serum (I'm not trying to be facetious) but not how much has been converted and used within the cells. However, if a patient does have a problem with Type 2 deiodinase their TSH will tend to be elevated (the pituitary is dependent upon Type 2 deiodinase) and of course their fT3 will be low.
Major conversion problems would be obvious from the blood tests, minor ones would be corrected by a small amout of T3 containing medicine such as liothronine or Armour Thyroid. Many of us require high doses of T3 in order to be well, personally I feel this has nothing to do with conversion and is more likely to be due to some form of hormone resistance.
As you mentioned some of the information is outdated. This the case with TT3 and TT4 assays, they are no longer used as the fT3 and fT4 are so much more useful in the care of hypo or hyper patients. Some labs will still do TT3, TT4 assays but these are mainly for research studies or are used along with radioiodine treatments in order to ensure all the thyroid has been removed in cases of thyroid cancer.
My doc only seems to check FT4 and not FT3 as well, just wondered why surgeries vary this way. Also my son who is 19 has had one instance of high TSH and subseauent positive peroxidase antibody thyroid result recently. Surgery wanted to wait six months but as I am also hypo and on 75 levo managed to get them to check again. Waiting on results. Think more investigations should be done on someone so young. He gets lots of knee pains which they put down to chondromalacia? Think it could be a hpyo thing though.
Also asked doc for a bit of T3 for me but was refused due to budgetary constraints! Asked cor NDT script but refused re CCG. Have ET diagnosed which I think is symptom of Levo for so long (about 30 yrs!).
Sorry about the several queries but you seem to be well informed!
Seems we wont be able to order meds on line soon without a script as companies are stopping this, possibly due to outside influences I suspect,
Even if the GP requests fT3 the lab will not do it. This is down to 'guidelines' publish by the British Thyroid Association and endorsed by the Royal College of Physicians. It's important to complain to these bodies. The fT3 is less important than fT4 but it is useful. If levothyroxine has been tried, including increasing the dose and it doesn't work I think it's good to try liothyronine but of course it's difficult to get a doctor to prescribe. I think this practical approach is bette than examining the blood tests which assumes doctors know what is happening, which currently they don't.
Sorry, I don't have any knowledge of the other disorders you mentioned.
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