I just wondered if anyone had any thoughts? I have been on levothyroxine for 15 years and normally my t4 would follow my tsh, but this time it has not, my tsh is 6.5 but my t4 is in range at 17.75. The doctor has suggested raising my dose of thyroxine, but i just wondered if there was anything else i should be thinking about considering that the two have not moved together as is usual
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JoannePA
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Did you drink coffee or other caffeine containing drink before the test? That can affect TSH.
Or do you take Biotin or a B Complex? If so this needs to be left off for 7 days before any blood test as it gives false results when Biotin is used in the testing procedure, which most labs do.
What is the reference range for your FT4 and has this changed recently?
Hi ya the ft range is 16 - 25. I havent done anything differently to any other thyroid test i have had. I have not taken biotin either. I think my ft4 was 24 last time they measured it, for me, it is usual that it changes, but it usually follows the tsh. Doctor seemed a little confused too!!
fT4 of 17.75 is near bottom of range , whereas fT4 of 24 is near top [16-24]. If t4 has fallen so much from previous test , it would be expected that TSH would rise ,(although perhaps no so much as 6.5, what is your TSH usually ? )
So i don't understand why the confusion. When you say T4 usually follows TSH what do you mean exactly ?
Just because both fT4 results are in range , it is still a big difference from24 to 17.75
Ok i see , Lol. that's just their answer to any results they don't understand.
It comes up as first suggestion on GP 'help' sites (and sometimes it's the only suggestion! )
No idea why it would go up that much , but my own results recently do several odd things that don't fit the 'rules', so i don't worry much about 'meaning' until i've had enough results to see a trend.
Recommend you get FULL thyroid and vitamins tested
For full Thyroid evaluation you need TSH, FT4 and FT3 plus both TPO and TG thyroid antibodies tested. Also EXTREMELY important to test vitamin D, folate, ferritin and B12
Low vitamin levels are extremely common, especially if you have autoimmune thyroid disease (Hashimoto's) diagnosed by raised Thyroid antibodies
Ask GP to test vitamin levels
Recommended on here that all thyroid blood tests should ideally be done as early as possible in morning and before eating or drinking anything other than water .
Last dose of Levothyroxine 24 hours prior to blood test. (taking delayed dose immediately after blood draw).
This gives highest TSH, lowest FT4 and most consistent results. (Patient to patient tip)
Is this how you do your tests?
Private tests are available as NHS currently rarely tests Ft3 or thyroid antibodies or all relevant vitamins
Hi yes i do do my blood tests that way, but thank you. my vit d hangs at around 64, my folate, i tried to get measured at the same time as i do fet folate anaemia, but they left the sample on the side in the lab too long so couldnt do it, my vit b12 for which i am on injections was fine. You are right they wont test t3 i will perhaps try private, thanks for the tips there. Just out of interest there though, why would the antibody tests help when i know i have hashimotos and have had for 15 years? Does the result change what they do this much later?
As you have B12 injections it’s recommended also to supplement a good quality daily vitamin B complex, one with folate in (not folic acid) may be beneficial.This can help keep all B vitamins in balance and will help maintain B12 levels between injections too
Igennus Super B is good quality and cheap vitamin B complex. Contains folate. Full dose is two tablets per day. Many/most people may only need one tablet per day. Certainly only start on one per day (or even half tablet per day for first couple of weeks)
Or Thorne Basic B is another option that contain folate, but is large capsule
If you are taking vitamin B complex, or any supplements containing biotin, remember to stop these 7 days before ALL BLOOD TESTS , as biotin can falsely affect test results
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