Help with blood timings please!

Hi ..I've managed to get emergency blood test done tomorrow as I'm not feeling well and have persistent tingling in my face and scalp (see last post!)...anyways as it is an emergency blood appointment it's the only one they could give me at 2.20pm or I would be waiting 2wk for it!Usually I would if booking myself do early morning and fasting but I can't do that at that time in the afternoon !!What should I do?I could manage to go without meds but not food?...also I haven't the opportunity now to stop my b vitamins with it being tomorrow and their doing b12 and folate!!Any suggestions? Thanks !

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31 Replies

  • Are you taking B complex with biotin in ? When did you take last ? You might get false result due to biotin if not stopped couple of dats before

  • Yes I am ..that's what I mean...because it's short notice I haven't had time to stop them!...

  • So probably not worth doing because you can't trust the results

  • Does it not just effect tsh ...?as mines supressed anyway because of ndt?....will it effect folate??

  • I don't think it affects folate.

    It does say in that link, above that biotin washes out quite quickly as is water soluble

  • Slowdragon I took the complex this morning ...I've been trying to raise folate and t4/t3 and ferritin and I'm only concerned with these and not you think biotin effects these?

  • Sorry no idea. That link says it varies depending on what labs use.

    24 hours may be enough

  • Thanks Slowdragon

  • Lozzer66,

    If the assay uses biotin then your results may be skewed. If biotin isn't used in the assay it won't matter. TSH will be very much lower at 2pm than early morning and TSH will also be lower after eating and drinking.

  • Clutter..My tsh is supressed anyways due to ndt ...will my t3/t4 be affected and will biotin effect folate ??...they are doing thyroid panel and vit d/b12/folate/iron panel ...if it only effects tsh I'm not concerned. .btw the biotin is 100mcg in the complex .

  • Lozzer66,

    FT3 will also be lower in the afternoon but FT4 is unlikely to be affected. See

    Biotin can affect any blood test assay which uses biotin as part of the analysis. It may be okay as long as you don't take it before tomorrow's test.

  • Thanks Clutter ..I didn't really want to wait 2wk for appointment as this tingling in my face and head/scalp is concerning me and I'm interested to know if I'm undermedicated /overmedicated and/or low on b12

  • Lozzer66,

    See if calcium can be added to the list. Low calcium can cause facial tingling and numbness.

  • As you have been taking B complex you won't get a true B12 result

    The active test is what you need and probably need a few weeks not supplementing

    NHS rarely do it. Blood has to be sent to St Thomas in London I believe

  • Clutter ...just a thought there a way of calculating what my true t3 picture is if my results are showing a certain level due to the late test and eating?such as adding a % ??

  • We might be able to look at what happens in a healthy individual - from research studies into timings and fasting/non-fasting. But you are an individual with your own particular genetic non-healthy oddities - otherwise you would not be asking questions here! :-)

    Any percentage would just be a guess.

  • Unfortunately so lol!..well I'll just take what I can from it and post on here when results are in least I'll get to know vit/minerals ..the rest I can go by temperature and how I feel 😉

  • Lozzer66,

    Not that I'm aware of.

  • Thanks anyways. .if only it was that simple lol!

  • Don't do the test or don't let them test thyroid hormones as the test will not be reialbe and it'll just have to be redone. Tingling is more likely to be low B12 but taking b12 within about 3 months of the test will spoil the results

  • Omg!3 months!!!☹

  • That long??!!!! How on earth are you supposed to raise b12 up if you have to leave of it for 3 months each time you have to test?...I can't understand that if it's water soluble and you can't overdose on it (as you just pee out )why it is so??sorry I'm confused lol!😕

  • I think for the active B12 test you need only wait a month, but the usual blood test seems to be very affected by supplements, so you can have a sky high blood results and still have neurological symptoms. You really only need to retest if you are going to stop supplementing or you need to persuade a GP to give you (more) injections. I've never bothered to retest while I am supplementing - I get an eye tic if I don't take enough and it goes when I increase again. The people on the HU Perncious Anaemia Society forum amy be able to tell you more.

  • Thanks that's interesting. ...🖒

  • Lozzer66 SlowDragon

    If the machinery and the test protocol uses biotin then extra biotin in the blood sample could affects results for lots of things, including thyroid function test results, B12 and folate. There are lots of other affected tests too - see this document, right hand column :

  • Just read and it says that as biotin is water soluble it leaves the system quickly and they retested after 13hr and the bloods had returned to normal....that's my take on it so if that's the case and I haven't had it for 30hrs then I should be ok?..that's my take on it anyway ...correct me if I'm wrong of course lol!

  • Sounds good to me.

  • ...sigh...sadly now I believe b12 is also squewed if you take b12 supplements before test too!...eeks!...!

  • Thanks ..just sat here now...ah well at least iron panel should be ok lol!

  • Hi Just wondered why you can't fast till mid afternoon? Drink water, go without food? Functional doctor's food pyramids now include fasting. Go a day or more without food or intermittent fast which is go 16 hrs between last meal night before and breaking the fast.

    There may be health reasons why you can't fast till after your 2.20pm app but that shouldn't really include low blood sugar (I don't think)

    Just mentioning incase you weren't aware how beneficial it is to your health to miss a days food or a block of hours.

    All functional doctors recommend in their lectures, in their books. You will find on you tube videos.

    I first started intermittent fasting (eating within an 8 hr period) because I read Paul Jaminet's book 'Perfect Healt Diet' yrs ago. excellent book. He describes how the bad chronic disease causing bacteria hiding in our system/cells, yeasts etc are starved of their supply of glucose during those non feeding hours and so their multiplication is compromised. Apart from giving your digestive system a break.

    So just saying, don't look at it as a harmful thing.

    I was listening to world famous cardiologist/heart transplantation/researcher this week, who recommends intermittent fasting and fasting for days also for health. And he personally eats one meal a day only - in the evening with his wife.

    I had always previously thought it was a bad thing to miss a meal, turns out the opposite and a bad thing for health and chronic health conditions to eat 3 meals a day every day.

  • Lynn that's interesting yes it happened ...the test was yesterday and I did fast I went from 7pm day before til 2.30pm after my blood was taken ...unfortunately now Ive learnt my supplements will have effected most of the mostly a waste of time it seems lol!

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