Re-testing bloods for levels

[Minimouse1]

Hi all, after a dose increase for hashi's & re-testing of bloods, I'm aware to not take levo for 24hrs prior & fast etc, however what is the advice about taking of vitamins and what exactly should my GP be 're-checking each time?? Thanks.

[waveylines]

No need to stop taking your vitamins. Make sure your blood test is first thing in the morning. A full thyroid panel should really be done but am afraid they wont do this on the nhs. Most likely the nhs labs will do TSH only & if that not right will do ft4 as well.....lol.

[helvella Administrator Thyroid UK in reply to waveylines]

Yes - there is a need to stop vitamins - if they include Biotin / vitamin B7.

In doses higher than ordinary food intake, especially very high levels, biotin can interfere with blood test results. (Depends on precise technology used.)

Although we see varying claims as to how long you have to stop taking biotin - up to a week. I suspect that two days is sufficient for lower intakes up to a week for higher intakes - but I have never seen proper research into how long megadoses can affect tests.

[waveylines in reply to helvella]

Interesting Helvelle -didnt know that! I take a low b vit complex which of course will have b7 in. Just had a blood test for thyroid vit D. Should I be concerned? I take the b complex (Thornes basic) to support my b12 deficiency -on injections.

[SeasideSusie Remembering in reply to waveylines]

waveylines

Medichecks answered a member's query about this recently, their reply is in the first post in this thread

healthunlocked.com/thyroidu....

I have read that it can be any blood test, not just thyroid, but as usual information is conflicting when you try and find an answer.

I leave my B Complex containing biotin off for a week for all my planned blood tests, whatever they are.

[waveylines in reply to SeasideSusie]

Ooooh. Oh dear -sounds like Im going to get false readings then, Mines a nhs test and because my tsh is always supressed they usually do the ft4 not the ft3. Will just have to see what happens and explain to doc if necessary have to repeat after stopping.

I know you wont be surprised but I have been amazed that since my B12 jabs my body temperature has risen to 36.7 or 36.8C - best I ever got was 36.4C. Never did that on B12 supplements whether sublngual or spray. Just goes to show the power of vitamins and their relationship and importance! But you know this very well Seaside Susie! Thankyou once again 😊

[helvella Administrator Thyroid UK in reply to waveylines]

Contact the laboratory and ask them if their tests are sensitive to biotin interference.

It is particularly difficult because test results can be affected in either direction. So you can't assume all results will be higher (or lower).

[waveylines in reply to helvella]

Thanks Helvelle. Good idea will do. 😊

[SlowDragon Administrator in reply to waveylines]

If you are taking vitamin B complex, or any supplements containing biotin, remember to stop these 7 days before any blood tests, as biotin can falsely affect test results

endo.confex.com/endo/2016en...

endocrinenews.endocrine.org...

[waveylines in reply to SlowDragon]

Thanks SlowDragon.....will re,ember next time.....too late this time as the blood test has been done.

[SlowDragon Administrator in reply to waveylines]

If result isn't to your liking, you may need to request new testing

[waveylines in reply to SlowDragon]

Yes I will indeed. Thanks Slowdragon. Am not sure if nhs will be willing to repeat (mindful of GPs & their budgets!) depends what labs say if biotin does affect their tests. If they wont will have to do a private test instead. I feel fine & my dose has been stable for years as has my blood test results, apart from some little hiccups due to manufacturers changing fillers etc...