What supplements to exclude before blood tests ... - Thyroid UK

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What supplements to exclude before blood tests and how many hours between taking metavive and testing please

Noelnoel profile image
5 Replies

Hello all

I’m having a blood test on Tuesday and I’ve remembered to stop taking biotin but I can’t remember what else I should stop. Also, I vaguely remember SeasideSusie saying I think, that there should be a gap of between 8-12 hours from taking metavive. Am I correct or have I mis-remembered?

Thank you

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Noelnoel
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humanbean profile image
humanbean

If the test you're having on Tuesday involves anything to do with iron or ferritin then, ideally, stop taking iron for 5 - 7 days before testing.

Opinions on how long to stop iron supplements for before testing vary a lot and I've read it should be 8 hours, 24 hours, 2 days, 5 days or a week, so if you stop today you'll fit the criteria from some sources.

Also, the rules used regarding fasting before a test for thyroid function should be applied to iron/ferritin testing as well.

Just something I remember reading... The problem with iron testing is that if you were to eat (for example) a cooked breakfast including eggs and bacon before a blood draw, and you absorbed iron fairly well, it would raise your iron and ferritin in the blood temporarily and possibly quite substantially. But if you were to forgo the bacon and eggs for breakfast for a week then your results might be substantially lower. Which is more real or more "true"?

Personally, I stop iron supplementing for a week before a blood draw, continue to eat my normal diet, and then follow the thyroid function test rules on fasting. And I try to be consistent from one test to the next.

Noelnoel profile image
Noelnoel in reply to humanbean

That’s helpful hb, thank you. I stopped iron yesterday so that will have to do

SeasideSusie profile image
SeasideSusieRemembering

Noelnoel

As Humanbean says, if testing iron then leave off iron tablets for 7 days.

Biotin or B Complex should be left off for 7 days before any blood test.

Any other supplements can continue but take after the blood draw on the day.

Metavive is, as you say, last dose 8-12 hours before blood draw.

Noelnoel profile image
Noelnoel in reply to SeasideSusie

Thank you SeasideSusie, that’s what I thought. Wasn’t sure about iron though so unfortunately stopped only yesterday

Noelnoel profile image
Noelnoel

Thank you SeasideSusie. That’s what I thought. Wasn’t sure about iron though so I stopped yesterday

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