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question about FT3, FT4 and TSH
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question about FT3, FT4 and TSH

hi there lovely, lovely thryoid forum people, I hope some of you may be able to help with this question, I'd love to get a few answers and see if there is a consensus opinion....

so here's the thing... I finally got to see an endocrinologist this week, after nearly a year of being ill.

I'm actually a lot better than I was but still have some symptoms, brain fog, swollen ankles, pain in feet, pins and needles on head, swollen stomach...I'm back at work but don't feel fully myself yet and I want to get properly well so I can get on with my life and my career!!!

She is finally testing my FT3 - I haven't been able to get this done before as my GP wanted to treat with synthroid till TSH and T4 looked okay and refer me to a specialist for further investigations including FT3 only if that didn't wholly work.

thing is, she was quite dismissive about the value of the FT3 test, even though she has said she will consider giviing me a trial of T3 medication, depending on test results. She's testing me for other stuff as well but she didn't sound like she expected any of them to show up (cortisol, B12, etc).

I wanted to see what you wise people on here thought about what she said:

"TSH responds to both FT4 and FT3 so if it is less than 1 (which it now is) you are not going to be deficient in FT3, normally we would consider FT3 conversion being  problematic if you had high TSH despite FT4 also being at the high end of normal...."

Because I know that lots of doctors in this field are not always very good and I want to know whether you think the above makes help me judge whether or not I am in good hands.

I know some of you may want to know my latest lab results so here they are:

TSH 0.4
FT4 19.5
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10 Comments Post a Comment
Avatar f tn
What's the range on your FT4?

My question is: rather than assuming that you are "not going to be deficient in FT3", why not test it and see?  The test is painless (you're already drawing blood for FT4 and TSH anyway).  The test is also cheap (about $10 for me after my health insurance "discount").  Why not test insteatd of assuming???
Avatar m tn
I think your doctor gave you the standard line about TSH correlating with both T4 and T3.  Also, many times they don't differentiate as to whether they are talking about total T4 and total T4, or free T4 and free T3.  This has been a subject of great interest to me and I have done a lot of searching for some statistical analysis that supports either idea.  To date the most definitive thing I have found is Fig. 6-7, in this link.

If you look at this data you can find that they have calculated that TSH has a high correlation to FT4 (as estimated by their calculations of FT4 index), for a given patient.  As I understand it, this means that for an individual patient, changes in TSH due to the pituitary signal, cause a predictable change in FT4.  Or, if the patient is taking thyroid meds, then a change in meds and corresponding change in FT4, will cause a predictable change in TSH level.  

Of course, if you look carefully at the data for all three patients together, you will also see that for a given FT4 level, there would be a huge difference in expected TSH level for even the three patients in the study, not to speak of the variability you would expect with a larger population of patients.  This is why so many members question the utility of TSH as a diagnostic or even a reliable predictor of FT4.  The study also assumes normally functioning hypothalamus/pituitary systems in the patients.  When you consider the number of times that you cannot assume these functions to be normal, that further reduces the utility of TSH as a diagnostic, yet we continue to see it used as such.

Back to the study again, the high degree of correlation of TSH on FT4, says that almost all of the variability in TSH levels for a given patient in the study was due to FT4. To me, this means  FT3 would  have no significant effect on TSH levels,  I think it's clear that this is contrary to what your doctor suggested to you, and is further reason to test for FT3 along with FT4, in order to be sure of your biologically active thyroid hormone levels..
1097839 tn?1344583542
hi both thanks so much for responding, I REALLY appreciate it.

Gimel thank you so much for that link and your insights on it. I will read it thoroughly before I see my doctor again next week... i see what you're saying about their conclusions about the variablity being primarily down to FT4, how can they then say Ft3 is equally linked, it's a right old minefield this whole debate with the medical profession isn't it....

Goolara I'm ,in the UK and under NHS treatment so don't pay for my own tests and can only get what the doctor orders. also, my GP requested FT3 testing in Feb and the lab just didn't do it, no reason given! Go figure!!! I didn't fight about it at the time as thought I'd get it done by the Endo, as she was referring me at that time and I expected the appointment to come through much quicker than it actually did.

I finally got to see an endocrinologist this week. She also said she would test FT3 for me but the results she's just sent me, in letter form don't include FT3.

they also don't give the reference range. I will of course be chasing to get all the numbers.

In the meantime I now have TSH 1.13 and FT4 17.7.

If the range is as it was at the start of all this it's  TSH .27 - 4.2, FT4 12-22.

The Endo did say that the reference range is not so relevant for me as I've been diagnosed hypo and am on thyroxine, she wants me to be the lower end of TSH range and upper end of the FT4 one.

I'm a little concerned my TSH is up and FT4 down since my tests in Feb (the results I posted earlier).

The good news (I think) is that she has agreed to a 3 month trial of T3 medication, I've been pushing for this since December. So next week I go back to my GP, to get the prescription for the T3 and discuss these pesky results....

I don't see the Endo again for 3 months ....

hey ho..what a battle it all feels like. sigh.
649848 tn?1424570775
You mentioned this in another thread and asked if you should begin another post, I agreed that you should, without realizing that this post was  here..........

I think your endo is dead wrong!!  First off, conversion can be an issue, regardless of the TSH; my TSH hit the basement floor almost as soon as I was started on synthroid, and it never did come back up, in spite of my doctor decreasing my med (that's a whole different story and he's not my doctor anymore) --- but even with my low TSH (less than 0.001), it was still determined that I have a conversion issue, based on my FT3 and FT4 levels.

The reference range is most certainly just as relevant for you as it is for anyone else -- if she doesn't look at the reference range, how will she know if your levels are at the upper end?  Of course, you are taking med, and of course, it affects your levels -- that's what taking med is supposed to do!!  A lot of us feel best when our FT4 is at (or near) mid range, and FT3 is in the upper 1/3 of the range.  In your case, you can't know where your FT3 is, because no one will test for it.

I would run as fast as I can from a doctor who will prescribe a T3 med without doing testing for FT3........I think you mentioned in the other thread, that she was giving you 10 mcg/day of T3 med -- I don't see how she can do that without even knowing what your current FT3 levels are.  She hasn't even confirmed that you have a conversion issue; that can only be done by doing testing for FT3 and FT4, then determining where your levels are within both ranges (high FT4 levels, with low FT3 levels would indicate a conversion issue).  In my opinion, TSH really has nothing much to do with that aspect.  My endo no longer even looks at my TSH because I'm on a T3 med, which often suppresses TSH even further.

In addition to that, you need to decrease your T4 med accordingly when adding a T3 med; did she happen to mention that little tidbit? Sorry, I know that sounds rather "snippy" and it's certainly not aimed at you, it's aimed at the doctor!!  Please talk to your gp when you get the script for the T3 med.  It's generally figured that for every 5 mcg of T3 med, you should decrease your T4 med by about 25 mcg.  If I recall correctly, you are at 125 mcg levo, so that would mean you would need to drop down to 75 mcg.

I also believe that 10 mcg of T3 med might be too much to start with.  In my opinion, you might want to start with only 5 mcg, then if that doesn't bring your levels up within a few weeks (assuming you can get someone to test your FT3), then you could go up to the 10 mcg.  It's also a good idea to divide T3 med into at least a couple of doses/day because it's a fast acting med and is out of the system in a few hours, so if you take the whole dose at once, it's likely to send you into a "tailspin" for a few hours, then when the med runs out, you could totally splitting the dose - say 1/2 in the morning and 1/2 around noon or early afternoon (this depends on your daily schedule), your levels will stay fairly constant throughout the day.  

I happen to be on T3 med and I went through all of this a long time ago. I know that if you don't do the proper testing and adjust one med (T4) to accommodate the other (T3), you could end up hyper very quickly.  I've only been "on the verge" of hyper, but even from that, I know that I'd rather stay slightly hypo, than to go hyper.  

You also mentioned that your doctor did some other tests; can you list the tests and the results for us, so we can comment on them?

By the way -- you said "my GP requested FT3 testing in Feb and the lab just didn't do it, no reason given!" -- are labs allowed to do that in the UK?  Are they really allowed to decide that a test ordered by a doctor is not needed?  Is that something the NHS allows/requires them to do - only running certain tests?  It's a scary thought to think that a lab can just "not do it" even though the doctor ordered it.  Is it possible that the doctor really didn't order it, even though he told you he would/did?  

1097839 tn?1344583542
Oh Barb, thanks for posting. I had been so plesed to get the result I was looking for from this endocrinologist, a trial of T3, that I hadn't stopped to think it is really odd she's prescribed it without testing FT3 and not mentioned any adjustment of my FT4.

I am so grateful for you and everyone on here sharing what you have learned, the more this situation goes on the less confidence I have in believing what I'm told by doctors.

so, nearly a year after I was first diagnosed hypothyroid.. I finally got an appointment with a specialist....

After the consultation she told me she was going to test: Celiac screen, TPO Ab, IgA, TSH, FT4, FT3, Vit D deficiency and cortisol. I'm not sure from what she's reported whether she's done that or not!

She has sent me a letter which says: normal haematinic screen, normal bone, liver, kidney profiles, random cortisol normal at 231, Normal FBC and lipid profile, TSH was 1.13, FT4 17.7.

I will chase for the details.

Despite me asking different doctors since October to get FT3 numbers and them being promised this time, she still hasn't given me any !!! Last time my GP requested FT3 from the lab and she apologised and said they just didn't do it, sometimes they don't do what a GP requests if they think the GP is askng for something that only a specialist could know was required!! I've no  idea what's happened this time,  I'll ask obviously.

I share your astonishment, you would imagine if a doctor requested a certain test the lab would have to do it...last time this happened I just thought I would be seeing an Endo soon and would get the answer then but now I'm just mystified!

From the tests she's quoted I don't know which one is the celiac one. Do you  have any idea? Smilerdeb on the other thread said "celiac test is IGG so that's been done" but I don't see that listed above so I remain confused, was Deb saying it's contained within the haematinic screen?

I was pleased to get the T3 trial agreed but now I have serious doubts.

She's suggested 10mcg a day of liothyronine alongside my 125mcg thyroxine.

I'm starting to feel a bit concerned about somthing else I'd love to get other people's view on: The letter states "we agreed that once we excluded an organic cause for her lethargy, then a trial of T3 therapy for 3 months could improve your symptoms,,,"

She mentioned in the appointment that T3 can be a mild antidepressant, is she saying she thinks I'm depressed and offering me T3 on that basis?

I'm not depressed at all. I've even been evaluated by a psychologist who confirmed I wasn't remotely depressed because I told my doctor I was happy to be evaluated for CBT if she thought it worthwhile quite early on in this whole process when she wondered if I had a bit of chronic fatigue going on and the psychologists report, after an hour of talking to me, is that I am am mentally fine though obviously having a tough time with this physical illness.

I'm wondering if the word "lethargy", which I never used and I don't feel I have, is some kind of code word for depression. What I suffer from is fatigue. I don't know where this lethargy word is coming from or what she means by it, if anything. It might of course just be sloppy English and mean the same thing to her but somehow I feel it is significant.

I don't want to start worrying unneccessarily when it might be that the FT3 test was done and I get the numbers when I request the full results and for some reason she just hasn't put them in the letter....but it all somehow smells a bit fishy as things stand.

I'm also worried because that was my one big chance to see a specialist. I've been waiting since December for this appointment and I won't get to see her again for another 3 months.

I'm also worried because she wasn't the consultant she was a Specialist Registrar which I think means she's not a qualified endocrinologist, she wasn't the doctor I was expecting to see that I'd been referred to, she said she worked in his team.... so have I basically been seen by a trainee....??!

I am feeling pretty confused  and anxious that my GP potentially knows less than I do about all of this by now...

any more thoughts?
Avatar f tn
I think the comment of Deb's that you're referring to is:  The normal haematic screen is for anaemia...IGA is antibody screening for Celiac (so yes she has done that)."   I was a bit confused also when I read your list of tests that the doctor had ordered vs. the list that she had reported reults to you on.  IGa is the celiac antibody test.  If the tests reported in the letter from your doctor were the only ones done, then IGa was also requested, but apparently nixed by the lab???  I don't think the haematic screen has anything to do with celiac...just for anemia.

I agree completely with Barb...especially that FT3 must be tested before starting T3 meds, and I'd start at 5 mcg and see how that goes.

We just had a similar experience to your "trainee" here.  My husband was referred by our PCP to a specialist.  When we arrived at the appointment, we were intorduced to "Ms. X", a nurse practioner.  She was very nice and very competant, but my feeling was that he had alread seen an MD, isn't seeing a nurse a step backward???  NPs can obviously do a lot in the health care fiield and take a lot of weight off of doctors, but isn't seeing a nurse when you see a specialist a bit of an oxymoron?
1097839 tn?1344583542
Thank you Goolara

hmm, it's weird isn't, I'm relieved it's not just me who thinks so. Hopefully when I get the lab report and see my doctor all will become clear but it's hard not to think it looks like a bit of a botched job. Especially because when I arrived at the lab they tried first of all to do blood tests for diabetes because apparently that's what they tend to do more of there and the nurses were just on autopilot. ...not  a very auspicious start.

Based on what you have both said I am very inclined not to just accept this 10mcg T3 prescription. It just doesn't seem to make sense.

I should say though that I wouldn't compare the doctor I saw to a nurse, she is a qualified doctor and a SpR in Diabetes in Endocrinology....I was expecting to see a Consultant though and an SpR is a doctor training to become a Consultant, Specialist Registrar I think it stands for. The whole thing really is not inspiring me with confidence though.

What happened with your husband's appointment? i would be really shocked, I have to say, if I went to see a specialist and ended up with a nurse, however good or senior they may be, that really seems wrong.


Avatar f tn
The NP was very competent, and I'm sure she had specialized training in the specialty.  I was just commenting that seeing a nurse after already having seen a doctor is not all that comforting.  I'm sure this particular NP has had experience in the specialty.  In that respect, she may have more knowledge than a specialist-in-training.  However, especially here, where we pay so dearly for our medical care, I think a specialist ought to be a doctor.  Period.  The nurse felt that my husband had been referred to the wrong specialty...saw nothing to warrant the referral.  She repeated some tests, and since nothing had changed since the last ones, suggested a three-month follow-up.  Where have we heard that before?

Yes, I agree, sigh.....
649848 tn?1424570775
goolarra said most everything I would have said.  Comparing the list of tests "supposed to be run", with the tests listed in your doctor's letter, it does not appear that you were tested for celiac.  

RE: the script for the T3 med - you might want to accept the script, but hold it until you get more answers.  It might only be offered one time; if you have the script in hand, you can get it filled after your questions are answered.  

You will need to lower your T4 med dosage when you start the T3 or you will only be asking for trouble.  In addition, starting at 5 mcg/day, as goolarra suggested would be much better.  It might take you longer to get where you want to be, but at least you will get there more safely.  

I think the deal with "lethargy" is double speak for depression.  Obviously, when we don't feel good, we tend to get a bit down, plus don't forget that fatigue is often diagnosed as depression. I had one doctor who insisted that I needed antidepressants because I was fatigued.  I told him I wasn't fatigued because I was depressed, I was depressed because I was fatigued.........He refused to listen and put me on Paxil; I took it for about 2 weeks and it made me so much more tired, I couldn't even get through a work day - he never did bother to check my thyroid, B12 or anything else - turns out I have both Hashi's and pernicious anemia.   Quite often, the T3 med makes us feel so much better that the fatigue begins to go away rather quickly, it might appear that a "depression"/lethargy has lifted.  I always wonder where doctors come up with some of the stuff they put in the official record - I had one doctor that put all kinds of stuff I never said or even hinted at.

There are some NP's or assistants who are very diligent in their field, but it is somewhat disconcerting when you go expecting to see a doctor, only to find that you get the NP or assistant.

I recently saw the assistant at my cardiologist's office, too -- I knew up front, though, that's who I would be seeing that day, so it was no surprise.  She was very conscientious and I felt comfortable with her; I've seen some, with whom I was not comfortable.
1097839 tn?1344583542
thanks so much again both of you, I rang the hospital today and they said they would post me my complete blood results so hopefully I'll get those in a couple of days and will share them then.

It does rather look as though she may have promised me one set of tests then done completely different ones. If that's the case I'm feeling inclined to make one holy row about it..but I'll think carefully first....

When I was first put on thyroxine, after my first tests in August, I was literally sent a prescription through the post by my GP. That might happen again with the T3 meds...if it does I'll sit on it as you suggest.  

I won't go and see my GP again till I'm clear about what I want to say.

Thankfully I don't feel too bad at the moment so I don't feel desperate about any of this, I want it sorted but I will take it one step at a time.

I'm starting to see why people get so upset about this stuff. I'm furious if she's putting me down as depressive, it's the last thing in the world I am!

thank you so much for your wonderful support and caring. I would literally be lost without the help I've had on this site.

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