Had follow up blood tests recently after levothyroxine increase from 25 micrograms to 50 micrograms. Did tests through both the GP and Medichecks (since they had the Thyroid function test on offer a few weeks back). I have a professional blood draw at a local clinic for the Medichecks test, rather than finger prick at home, to ensure the best outcome.
I follow the suggested blood test protocol on here: morning test, last LT4 tablet 24 hours before... the only caveat being, this time I could only get a late morning GP booking so I had to have my appointment at 11:25 and I had a running client that morning so I really had to have a cup of tea and an energy bar before going to the GP, otherwise I would have keeled over - so the time difference since my last tablet for the GP was about 27 hours and I had had a tiny amount of food beforehand (the protocol for the Medichecks blood draw was 100% correct).
The GP did request a FT3 analysis and annotated that I was querying that I might be a poor T4 to T3 converter (based on previous Medichecks results - and further supported by the latest Medichecks results). The GP's phlebotomist confirmed that there was a TSH/FT4 request AND a separate FT3 request... she did three sequential blood draws, which I was not expecting, as the GP had also requested a full iron panel - that I had requested previously, but was refused at that time - AND a B12/folate test - that I think was accidentally carried over from the B12 test I recently got separately because it was missed in the previous bank of tests.
ANYWAY... what happened was, rather than doing TSH/FT4 and FT3 analyses, the lab did TSH/FT4... and TSH/FT4 again!!! So the same blood draw by the same phlebotomist, at exactly the same time, under identical conditions. 🙄
Now... take a look at the two sets of data in the yellow highlighted boxes in my results spreadsheet. These show the two sets of reported results from the same blood draw. The TSH readings vary by 0.1 (which equates to ~2% variation) and are both still high through the range... BUT the FT4 readings vary by ALMOST 100% (actually ~93%). I find this absolutely crazy! I cannot comprehend how such different readings can be generated from two blood samples taken at exactly the same time. The FT4 values put me either 31% through the range - so needing a dose increase (on paper) OR 114% through the range, i.e. OVER range - so needing a dose decrease (on paper).
This is RIDICULOUS!
[Incidentally, I *feel* like I need a dose increase... remains to be seen what the GP says 😉]
Written by
ERIC107
To view profiles and participate in discussions please or .
I will be asking for a 25 mcg increase... I am interested to find out which results she'll try to go by, though. The last time I spoke to her - to request the FT3 test (which, to be fair to her, she did request) she said finding the right level was "not only about the numbers but also about how the patient feels... that's the ART of medicine" (an actual quote) - so I'm hoping she will stand by her comment.
She has been very supportive so far - and I have no reason to expect she will change, which I know is not the experience of everyone on here... so I do feel very lucky in that respect.
She sent out a feedback survey after our last telephone chat, so I did give her a good write-up 😊
I am so glad you posted this as I am having similar ridiculous over the various blood tests via GP or finger prick methods. No consistency whatsoever and one is left with pity idea of which, if any test to trust!
Sorry to hear you're having an equally crazy time with tests as I am!
I know that biological tests are notoriously difficult to make reproducible, due to the variability of body-related samples... but we both appear to be finding HUGE variation where there really shouldn't be any.
Ironically, with mine, they did their own "internal audit" by managing to make the TSH tests very reproducible but totally messed up the - more important - FT4 tests!
It makes it so hard to trust the results we're being told 😑
I know. Assuming it’s a typo error and it’s 9. It still is so different from your Medichecks one too.
It is also unusual for the lab to do the same test twice. I think the first step would be to have another test. Or, forgo the test, and go with how you feel and I’m sure your GP support.
Actually - great question! I didn't even think of that... so I really appreciate you asking.
These results are taken from my access via the NHS app to my medical records - in the test results section. I don't know how those results arrive in the digital medical records. A transcription error is a very good shout. Thank you! 🙏😊
Yes in that case I think they just make them available. And I would expect the results go in automatically when analysed, - so unless there’s a way they could be modified by accident somewhere asking the line it’s perhaps unlikely. Still, worth a guess as it wouldn’t have been quite as wildly out!
The more I think about it, the more I think you and HealthStarDust hit the nail on the head and it's a typo. I think the actual duplicate reading *could* be 10.4, since the number 9 is adjacent the zero on a keyboard - but I won't know for sure until I ask the GP.
I would question if both sets or results were actually yours, or did someone else's results get mislabelled or something. It would be very strange for the lab to test the same blood twice.
If I were you, rather than asking for an increase based on the lowest of these results, I would ask for a retest to find out which one was correct, and then base your dose request on that.
Thank you! These are all good points that I will raise. The overall lab request did contain two separate thyroid-related requests as the GP asked for the usual thyroid function test, intending it to be the TSH/FT4 analysis, and then separately asked specifically for FT3 to be tested - with an explanation as to why she was asking for that... to try to encourage the lab to agree to test FT3 as well. That could be where "the wheels came off" - so to speak.
I think, ultimately, I would base my request for a dose increase based more on how I feel, rather than the absolute numbers coming back. I currently feel like I need to go up - a bit (it's like the fog is clearing... it's now just a light mist! 😊)
But doctors don't care how you feel. They know nothing about symptoms and believe that if your results are anywhere within the range, there can't be anything wrong with you.
The separate request for FT3 may explain why the lab did two lots of tests - although I find that rather difficult to believ - but it doesn't explain the massive difference between the two FT4 results. Did the phlebotomist do two separate tubes of blood? I cannot imagine that they would do the tests twice from the same tube of blood. That doesn't make any sense. And, in any case, FT4 and FT3 need to be tested from the same blood. But, pity they didn't do it because it would have been interesting to see if there was any difference between two tests for FT3.
I'm hoping I've lucked out with an empathetic GP - she has already told me that finding the right level was "not only about the numbers but also about how the patient feels... that's the ART of medicine" (an actual quote) - so I'm hoping she stands by that statement! 😊
The phlebotomist took 3 tubes of blood (it was a surprise to me that that many were needed!) for 4 requested tests: "Thyroid Function", "Free T3 (with an explanation that I was querying that I might be a poor converter)", "FBC and full iron panel", and "B12/folate". The phlebotomist read out to me directly from the request form as I'd ask her what was being requested.
I totally agree with all your comments - nothing about it makes any sense... and it really has been a missed opportunity to see what an NHS-reported FT3 value was.
I would ask the GP to contact the biochemist at the lab for an explanation. Energy bars may contain biotin which can affect results but not two from the same person at the same time giving different results. It would be better to eat a normal meal than an energy bar just in case.
Yes - I certainly intend to discuss with the GP to find out what she thinks is the best way to find out what happened.
When I said "energy bar" I should have been clearer - it was a simple Nakd bar... so only squashed fruit and possibly some nuts, depending on what flavour it was - maximum four, or so, ingredients. Just a quick snack so I could get out of the door and to my appointment 😊 It's a good point about the highly processed bars marketed as "energy bars" - you're absolutely right, they often are fortified with vitamins and other "pep-up" molecules!
it could have been a typo when entering the numbers on the system or even someone else's results. I'd go for the former as the TSH was about the same in both cases. The analysis machine may store the data so they could check it.
Could this be to do with the machinary they bought in that enables them to do multiple simultaneous testing. I know there's problems with B12 inaccuracy missing low levels.... Wasn't aware that they're messing up thyroid tests too. Your results are bonkers and basically of no use. I'd want an explanation from the labs. Doubt it will impress your GP who is likely to ask for a repeat. Fasting is fasting.... Just try to get an earlier appointment. I go to a drive in because of the problem... Nurses app start at 9 & frankly even an early so called app I rarely got seen before 10am. . The drive in is a pain as 16mile round trip but at least I get tested early on. Lol... Xx
I have same, blood test at gp would only be 5 mins walk but impossible to get a choice of times, so I get a lift or taxi for appt at phlebotomy centre mikes away, but I’m able to book it online with full choice of times. Have to do before 8am else you get stuck in the traffic.
Good point. That is something that the lab would need to review - it is possible that there could have been a simple technical issue with the actual volume of sample extracted for analysis. The large batch processing tends to involve multi-head pipettes and/or robotic extraction tools to speed up sample extraction and prep. - each of which could, on rare occasions, have an air bubble or other sampling issue. B12 is NOTORIOUSLY difficult to analyse (it's a world I inhabited for a period of my lab-based working life... it looks beautiful - a deep red/purple colour - but a pain to deal with! 😂)
I certainly agree that, with two wildly different data points, the results are useless!!!
I'm usually a late(r) riser and naturally break my fast later than most people. The 11:25 appointment wouldn't have been a problem were it not for a re-arranged exercise session that had to take place earlier that morning. I'm happy to leave the very early appointments for folks who really need them... it all just fell wrongly this time.
That's interesting Eric re the B12 analysing. Do you know why they set the range so wide? I attended a talk on this the other week and was shocked to hear that the muti headed machinary is coping badly with B12 testing and inaccurate, giving higher results than was really the case. The suggested answer was two other tests to cross check, Homeostaine and can't remember the other!! I understand labs are pulling their hair out with the b12 issues. Not helped by the lower level being set so low & doctors being very literal about the interpretation of such tests.
My area of expertise was vitamin formulation in things like baby formula, vitamin drinks, supplement powders, etc. - so a bit outside of biological testing... but, from the world of nutritional supplements, B12 is fundamentally one of the lowest components tested and is often in the presence of other high level components (Vit D, etc.) - I think the same would be true for biological systems. Testing for something at a very low level in the presence of something at a very high level is very difficult. A wide range is often given purely to make sure that the "target" is hit... imagine throwing a tennis ball at an archery target - if you have to move a very long way away, so the target looks tiny, it's much harder to hit. One way to make it easier to hit is to make the target bigger - BUT the slightest interference, such as a gust of wind in the tennis ball analogy, causes a big problem.
From my point of view, it's a fundamental problem that's inherent in the wish to test B12 levels. The main way to move towards overcoming the challenge is investing in more sophisticated analysis equipment (more sensitive, more reproducible, etc.) BUT this is expensive (I used to work for an instrument manufacturer - it's *eye-wateringly* expensive)... so if there's a cheaper test, albeit with more problems associated, then most commercial labs will go with the cheaper alternative - until it starts to negatively impact their business!
Thankyou. That makes total sense. B12 testing never showed me as under the range, just low in range. On that basis GP wasn't allowed to treat despite me having multiple symptoms associated with B12 deficiency. I had to see a neurologist to get B12 jabs approved. I felt the delay (7month waiting list to be seen) was far too long & at risk of pernenant damage so self treated to great effect. Neurologist agreed when I finally saw him. It does leave a big gaping whole in the alleged recommended frequency of B12 jabs if testing isn't reliable. Luckily my jabs are daily, infact twice daily but I pay for the extra. From this I assume I'm unable to retain b12 for whatever reason.
You're welcome! Sorry to hear you had such a terrible time with your B12 levels... for something that's SOOOO vital to our whole body, it's a tricky little blighter is B12!
Really glad to hear that you seem to be on the right track with B12 now, though.
Oh yes thankyou, fourth year of treatment. Transformative but unable to reduce frequency.. Yest the NHS has the notion that every 2, or 3 months is frequent enough on their guidelines.. Such nonsense!!
I would directly contact the lab. Labs do keep samples (frozen) for some time and in the context of a serious issue might re-analyse. (Could be too long - I think officially it tends to be one or two weeks but I doubt they are strict about that and could well keep them longer if they don't urgently need the space.)
Some labs have more than one analyser. That would only be known, and the one used for each sample checked, by the lab.
I'd also consider reporting to the CQC and UKAS. Not so much as a complaint more to ensure the possibility of a serious issue is seen by them. After all, if a batch of reagents were dodgy, this might occur for some samples across a number of labs. Then disappear. And only a country-wide overview would be likely to properly reveal what is happening.
I will definitely, in conjunction with the GP, look at contacting the lab and reporting the results. My immediate thought was that they need to do a review of their protocols - both analysis and sample review - as, if the error arose at the lab end, they should have picked it up: two such disparate results from the same patient.
I don't know which lab my local Practice uses so I would need to find out from the GP, and find out if she wants to pursue it or if I should (or even both of us). Many thanks for providing the link.
I definitely think you should be going up to 75mcg. Especially if you think you need a dose. Have a look at some of my earlier posts. I took a bit of convincing my doctor to raise mine. I'm now on 100 mcg. I now finally feel good.
Content on HealthUnlocked does not replace the relationship between you and doctors or other healthcare professionals nor the advice you receive from them.
Never delay seeking advice or dialling emergency services because of something that you have read on HealthUnlocked.
Can anyone throw any light on why blood results are so different 
My TSH has gone down but so have my FT4 and FT3
Crazy Underactive Thyroid, Maxed out on Meds
Crazy new numbers being thrown my way. 
Finally been labeled as a crazy due to hashimoto's and it was heartbreaking
