Results of TSH & FT4 taken same day at 2 different hospitals:

Following some discussion about timing of TFTs I'm posting results taken at 2 different hospitals and 2.5 hours apart last week. Both tests were fasting because of cholesterol morning draw:

11.00 TSH 0.17 (0.35-5.5) FT4 17.2 (10.0-22.7)

13.30 TSH 0.13 (unknown) FT4 18.3 (9.0-19.0)

I intended my 2nd test to be drawn at 13.00 when TSH is lowest as GP had agreed to reduce my T4 without endo's consent and I didn't want him to get a row.

Original threads

Last edited by

30 Replies

  • These are normal variations. TSH is 'pulsatile' which means it's release isn't contant, it fluctuates a bit. I recently read a paper (lost it for now) which stated something like you need to take about 15 blood tests to arrive at an average result that is accurate to five percent. Small differences (< 10%) in thyroid blood test results are not meaningful.


  • Yes, I realise they're normal fluctuations and accord with the circadian rhythms which fluctuate a lot over 24 hours (as shown in the graphs in the links).

  • Hi It is due to the assay , also time of day. Normally T4 should be top third of the range, wherever done. Also you do not mention FT3 ( free T3) vital for the correct treatment.

    best wishes,


  • Didn't mention FT3 'cos labs didn't test, Jackie :( I agree with you that there isn't a full picture without it.

  • It is annoying. Some hospitals do it. My cardiac do without my permission, usually when I have just taken it, makes it double! Just as infuriating.


  • That's just a waste of resources but could be dangerous if they attempted to treat or alter meds on that result.

  • yes, I am petrified of that. having a big row with Cardio at the moment, they want to disconnect my ICD, certain death, etc etc , meeting tomorrow to try and combat their lies, not much hope of that!


  • I had to look it up Jackie. Why on earth would they disconnect it? Surely it would kill you?

  • Hi That is their idea as I am dying any way. However, I cannot live for an hour without it and I am not going to commit suicide. However, they are over ruling me!Especially as often in a coma and then i am powerless.They have been to the ethics committee, evidently my wishes do not count! although I have the support of all my many consultants and brilliant private Cardio, still powerless.I am extremely complicated and they do not understand my 12 co morbidities etc. So, they are going for the easy option. !I will see how the meeting , today goes, but I dread to think. I may just leave, not easy in a wheel chair!

    I knew you would need to look it up, but so complicated to explain!I have to for many docs and of course, nurses.

    Best wishes,


  • Jackie, I'm very shocked. I imagined ethics committee's ruled to determine when patients lacked mental capacity. Have you contacted your MP? If you requested removal I could understand their dilemma, but to do it this way? Do they think removal will benefit you in some way? How can they remove it without your consent?

    Jackie x

  • Shocking

  • Hi They can, and it is not unusual.My own good docs agree with me, but cannot interfere!!!!He told them all lies and also the clinical director, I know this for a fact.

    I also had the sham meeting today. When I proved everything he had aid to be untrue, but useless.My good consultants want me to take it much further but exhausted.All the wrong treatment has not been documented, obvious nothing I have sent or given. has been read. I know some things that have happened are illegal but if they do not document it all, as they do not, nothing I can do..

    I am actually too ill for these battles but it is my life. I do exactly what my decent consultants tell me to and they also say I have to keep myself alive and not trust ( their) hospital!

    I cannot go elsewhere as the "best" for all my co-morbidities!You can imagine what some of the others are like. It is partly as I am extremely complicated.

    Imagine what it is like for people without a good brain or mentally kill!

    Thanks any way.

    Not beaten yet , but struggling!


  • I'm still struggling to understand how removal could possibly benefit you. Pacemakers are never removed and this is a form of it.

    Sorry you're having this battle when the important one is to manage your health.

    Very best wishes,

    Jackie x

  • Hi, It is because of the defibrillator, they say it is uncomfortable for the nurses to see it reviving an almost dead patient! Must not have that, at any cost!



  • Incredible! Why have defibrillators at all if they're disturbing to nursing staff? Oh yes, they stop patients from dying of heart failure. Nurses need to get over themselves or get a different job not kill you off because you offend their sensibilities.

  • My ICD by defibrillating has saved me with my last 2 arrests, I had 2 before that and very lucky. Actually a good Cardio. Only one in about 20 !! Cardiac in hospital is such a nightmare. Unfortunately I have a lot of emergencies and have no choice.When dying in there, they just pull the curtains and ,leave me on my own.

    This is one of the best hospitals in Europe!!!


  • Doesn't sound like it to me. It's not even back door euthanasia when withdrawal will kill you. It's not right.

  • Hi Probably a mistaken but just e mailed them and asked for details of the meeting , after advice, to include all the false accusations.!!


  • Hi

    I think that you feel that your TSH should be lower in the second test. However, your own circadian rhythm for TSH may not have very high peaks and troughs. In some some individuals the pulsatile nature of TSH is not very apparent. If you look at the graph in the link below for subject 34 you will see that there is only very modest changes in the amplitude of the peaks and troughs.

    I also suspect that if a patient takes replacement meds in the long term that the pulsatile secretion pattern may become skewed dependent on timing of replacement meds - I have no evidence for this, but it makes a lot of sense that the secretion patterns for TSH could be altered as a response to replacement thyroid hormone timing.


  • I wonder whether lack of thyroid makes much difference too.

  • Afraid that without knowing the reference range, the very modest numerical difference between 0.17 and 0.13 could be reduced or expanded by the second TSH range starting lower or higher! If you see what I mean.

    If the second TSH test had a range 0.25 to 4.5, then you are looking at where 0.13 falls in the "below range" 0.00 to 0.25. That is, almost exactly halfway between zero and bottom of range. If the second test had a range 0.45 to 5.6, then it is where 0.13 falls between 0.00 and 0.45. Which is not even one third of the way between zero and 0.45.

    I appreciate that this is a very mechanistic approach but is meant to show how difficult it is to interpret the results.

    Other than this, the "normal variations" arguments do seem quite strong. A shame your first test had not been at 08:00 (or earlier!) - that might have made the second test look very different instead of only marginally so.

    By the way, I have recently had a short period when I felt very slightly over-dosed on levothyroxine. I absolutely hated the feeling. If I had to choose between feeling like that for years and feeling much better than that, I am fairly sure I know which way I would go.


  • I've never known the TSH range as it's always been under <0.1.

    The timing exercise worked out the way I wanted and I would certainly advise anyone borderline or requiring an increasing to test at sparrow's fart.

    I don't think I'm overly sensitive to meds but 18 months of over medication had a very unpleasant cumulative effect and made me very ill indeed. I've certainly improved my health and well being since my 'detox' and hope that I'm on the road to recovery now.

  • Yep - understand that - if it is at limit of detection, the range obviously doesn't matter!

  • I had to have a blood test done for endo and for GP so decided to have them done on the same day (save me having to go through it twice). It was the same blood, taken at the same time, at the same hospital. The GP got his results which showed I was overmedicated. The Endo got his results which showed I was undermedicated. So one of the testing equipments was faulty. How long it had been faulty nobody knows nor how long they will still be using the faulty one because nobody cared when I pointed this out. The endo said I should have more thyroxine and my GP refused to prescribe it because his test results showed over medication. Even when I told him about the different results he took no notice. I guess he either didn't understand or was not listening to me or just didn't care. He was sticking by the results he had in front of him whether they were faulty or not.

    I phoned the lab about three weeks later pointing out the discrepancies. The chief of the lab did not understand what I was saying. She said it is possible to get two different results from two different machines. I tried to point out to her that although the numbers might be different it could not possibly be from the same blood that one could show hyper and the other hypo. Eventually she said she understood, but that could be just to get rid of me. She did offer to do another test for me. Unless they recalibrated the faulty machine it would be useless as I would not know whether that result would be right or wrong.

  • That is scary!

  • Hey Clutter

    That's interesting.those 2 tsh results are really close despite 2 and half hours between them!

    Now if you could kindly build a time machine,go back in time and redo them without fasting I would really appreciate that :D

  • If I could do that, I'd go back far enough to uninvent the "exquisitely sensitive" TSH test :-D

  • 8 - 8-30 am is best as TSH would be higher in the range and FT4 lower.

  • It is if your borderline hypo, Muffy, or want your meds increased.

    I wanted to avoid a meds increase and looked to test when my TSH would likely be lowest.

  • Sorry Clutter, got the wrong end of the stick.

You may also like...