WILL HB DROP SLIGHTLY AFTER BLOOD TEST

[Kerry-78]

Hi

I posted here a couple of days ago about hb b12 and sugary, the anestetist is now not worried about my b12 buts wants hb to ideally be 110 but may still consider surgery at 100. I'm going to the Dr's this morning for another b12 and was wondering if I should ask for another blood test to see if my hb is going up since I've increased my ferrous fumarate intake. I'm having a blood test next Friday, this is the one they will take the hb reading for surgery, my question is if I have a blood test today just to check what it' doing will this affect the one next Friday ? I know they only take a small amount but dies the hb level drop once blood is taken ?

[Foggyme Administrator]

Hi Kerry78. No, the small amount of blood taken for a blood test will not affect your haemaglobin levels. However, there is little to be gained from having it tested today and then again next Friday because it's the one next Friday that will be used to assess Hb status prior to surgery.

'The anaesthetist is now not worried about my B12'

I wonder if your anaesthetist is aware that the anaesthetic gas nitrous oxide can be detrimental to those with B12 deficiency (which you have).

Here's why: nitrous oxide deactivates all B12 in the blood. Following B12 injections, your serum B12 levels (in the blood) should be very high. However, if you have nitrous oxide as part of your anaesthetic, this will de-activate all the B12 in your blood. Anybody who does not have B12 deficiency (or low B12) can simply draw more B12 from the liver BUT those with B12 deficiency or low B12 are unable to do this because supplies in the liver are low (they have to rely on supplies of B12 from the blood - via injections).

So...if you have nitrous oxide, this will deactivate all the B12 in your blood and you will once again become B12 deficient and experience the symptoms of B12 deficiency again. There are two remedies for this:

A) ask your ask your anaesthetist to ensure that you are not given nitrous oxide as part of your anaesthetic (not an issue since there are other gasses that can be used instead). Good idea to write 'no nitrous oxide' on your consent form and ask the prep-nurse to put a red warning wristband on your arm.

B) Repeating loading doses of B12 after anaesthetic where nitrous oxide is used replenishes the supply of B12 in the blood.

Sadly, not all anaesthetists are aware of the above implications when relying on an injected source of B12 (rather than supplies directly from the liver).

Here's a link to further information (though this speaks to low B12, rather than when B12 is obtained from injected source...though the logic should be self-evident):

gov.uk/drug-safety-update/n... (Low B12 - Nitrous Oxide Contraindications)

Hope the Hb levels come up sufficiently for your surgery to go ahead and that all goes well for you.

Good luck.

[Kerry-78 in reply to Foggyme]

Thanks for your reply, I decided against having another blood test today and just to have the B12. I appreciate the information on the nitrous oxide and I very much doubt the pre op nurse and perhaps even the anestetist are aware of this as both seemed very vague about the situation !

[Foggyme Administrator in reply to Kerry-78]

Sadly, it's not unusual to hear that Kerry-78. At least you're now forewarned and can make sure that you don't have any nitrous oxide 😖😉.

Might be a good idea to print the safety update notice and take it with you...they might learn something.

Good luck,with it all...hope the op goes well 😉.