Does a B12 injection affect a blood test

[KatyMac68]

Got my blood test tomorrow morning at 7:50

I've been off all my vitamins since the weekend but I'm over due my B12 injection, can I have it today or will it skew the results

I've had 12 weeks at 25mcg and 8 weeks at 50 mcg so I really don't want to stuff it up

[McPammy]

I always have my b12 injection after my bloods are taken for testing.

Not had b12 injection prior to a blood draw.

[Musicmonkey]

Have the B12 after your blood test result? If it contains Biotin it can affect the result.

[helvella Administrator Thyroid UK in reply to Musicmonkey]

I'm not aware of any ordinary B12 injection containing biotin.

[Musicmonkey in reply to helvella]

I don't know what's in a B12 injection, but the poster needed a quick response, so I offered the only help I could in the time available. Thanks for clarifying 👍

[KatyMac68]

Thanks guys

I didnt do my b12

But I did stuff up my blood test

I remembered my blood test

I got there on time

I forgot to not take my thyroxine when I got up

I was thinking only the other day how pleased I was to have not forgotten to take my morning one! (Evening another story)

[dottyb09 in reply to KatyMac68]

Your last dose of thyroxine should be 24 hours before a blood test.

[KatyMac68 in reply to dottyb09]

I know, I have problems with remembering to take tablets and I've some how got into a routine

I also have issues with taking them twice because I thought I forgot

[CoeliacMum1]

I’ve had B12 injections well over a decade as well as having Hashimoto’s well over a decade too , it’s never bothered my Thyroid results that I’m aware of… it will however skew your B12 results if having that done … I only now have tests annually, so I do try to get blood test done before if at all possible for more accurate results as you will get abnormally high B12 results if testing that … I know my B12 results in a similar situation years ago caused a few hiccups, and they actually stopped my jabs, only for months down the line deficient again 🤦🏻‍♀️ and back on them 🙄

Biotin (vitamin B7) is the one responsible for altering tests, due to the procedure in labs (I think) …but does not alter thyroid function.

[KatyMac68]

Thanks, that makes sense CoeliacMum1 glad to know it won't affect it

Taking my tablet will tho - such a numpty

[Ukie]

This is about tablets not injections, but it’s Medichecks advice from this week.

Medichecks advice regarding B12 not to be taken for 2 weeks before blood tests.

[KatyMac68 in reply to Ukie]

That's interesting!

I normally do one a week but had forgotten for 3-5 weeks (& then wondered why I felt so crap)