iron's role in B12 injections - Pernicious Anaemi...

Pernicious Anaemia Society

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iron's role in B12 injections

Kerrierach profile image

Could I ask your opinion please on iron? There are two conflicting views: B12 injections bring down iron levels and B12 will help absorption of iron and therefore increase them. I don’t have and never had macrocytosis. If iron, like potassium, is used in the formation of red blood cells only if there is macrocytosis, does it imply I don’t need to worry about iron? Or, is iron used by all B12 injections? Related to this, will B12 injections work if my iron level is low?

I don't really need advice on iron supplementation or iron testing - it's all in hand. I also know people are not medically trained but if anyone could give me their best guess I'd appreciate it - there seems to be a lot of sense written on here. thank you

14 Replies

I found my ferritin levels dropped from first blood test that revealed low b12. My ferritin was 62. The next blood test 3 months later my ferritin ad dropping and reached 29. I believe it's used somehow in repair work. Others think of tou csnt absorb b12 tiu often cant absorb other things. Folate vit d ect.

My blood result at the start diesnt takky with thus unless it started to be deleted at alot slower rate than b12. My folate was 9 at the start.

That is my experience. I didne have macrocytozis either .

So I think it's best to monitor with repeat bloods 3-4 months later to see whars happening

Kerrierach profile image
Kerrierach in reply to Nackapan

Thanks for serum ferritin is often on low side and I’ll try to monitor it


Nackapan profile image
Nackapan in reply to Kerrierach

Thankyou for the pm. I've nothing really to add to what I've put on the main forum. I'm still hoping for improvements.

Of those two conflicting views, both are wrong.

Yes, if you have macrocytosis then the body's need for iron will be slightly increased during the first few weeks of treatment. But, unlike potassium, the body has ample stores of iron, so levels will not be depleted to any extent.

B12 does not significantly increase the absorption of iron. A B12 deficiency is often accompanied by an iron deficiency. But that's because Pernicious Anaemia will be accompanied by a lack of stomach acid, which reduces the absorption of iron.

Your iron levels will have no bearing at all on whether your B12 injections work or not.

Kerrierach profile image
Kerrierach in reply to fbirder

Thank you. I’m happy to have received an answer than finally makes some sense. I’ve wasted a lot of time and energy stressing over potassium and iron.

Sorry if this ends up in really simple terms but I'm feeling too rough this morning due to antibiotics for a jaw ulcer to get complicated - please don't think I'm suggesting you can't grasp something more challenging!

Our bodies are made of cells. Although there are a range of different cells for different functions, every cell is made up of molecules (groups of atoms - the smallest units that we know about and defined in the periodic table - joined together).

With the exception of red blood cells, cells have a nucleus which holds the genetic information as DNA to enable them to split and make copies, and mitochondria where chemical reactions take place to release energy. (Think about chemistry lessons where if you mixed things together they got hot, maybe gave out light and the exciting ones shot across the room = releases of energy!).

Nerve cells are very specialised cells which transfer electrical impulses around your body, similar to the wires around your house, using atoms with an electrical charge, including potassium and sodium.

Red blood cells do not have nuclei or mitochondria so they have more space for haemoglobin molecules, made up of lots of iron + other atoms, which carry oxygen around the body so every other cell can use it.

Vitamin B12 is a big, very special molecule (collection of atoms) that is used in all the functions of all the cells in our bodies, hence why it is so important.

As the processes of cell replication, nerve function and energy release that use B12 all need a wide range of other nutrients to work properly, it means that nothing will function fully if something is in short supply (it becomes a "limiting factor").

So while each vitamin or mineral molecule has its own specific uses within the body, they are all needed to supply the atoms which make up the building blocks of cells or provide the fuel for energy release within them.

So, in short, despite what fbirder says, yes, vitamin B12 use in the body IS indirectly dependent on iron, as it is on potassium, magnesium and all the other minerals, and folate, vitamin D and all the other vitamins.

In some cases, eg folate, they work directly together, in other cases they have an indirect link, but the end result is that no matter how much B12 you put into a body, if that body doesn't have enough iron (for example) the processes that use the B12 still won't work properly.

In practical terms you may benefit from a broad spectrum multivitamin and mineral supplement, plus extra folate and maybe potassium, magnesium, iron and vitamin D, ideally from your diet!

I hope this helps - if not I can try to make it clearer another day!

Yes that’s is important - everything is interconnected. I’ve started supplementing iron, thank you.

Foggyme profile image
FoggymeAdministrator in reply to Kerrierach

Merrierach. Just so that you are aware...supplementing with iron can be dangerous if your body doesn’t need it. This may cause Iron overload - a dangerous condition that is difficult to reverse (especially if iron gets lodged in the joints and tissues).

You say that your iron is often on the low side? If you mean ferritin, this is only one marker of full iron status. It’s possible to have low ferritin but still have too much iron in the body ( as measured by other iron markers - found in a full iron panel test). Chronic disease can also make it difficult to properly asses and determine the presence if iron deficiency anaemia.

So, it’s always better to supplement iron only on the advice of a medically qualified health professional. They will be able to assess your full health and iron status and won’t rely on one sometimes imprecise (ferritin) measure of iron status.


Kerrierach profile image
Kerrierach in reply to Foggyme

Foggyme, thank you for your advice. I know it can be dangerous and it’s been another great stressor and cause of health anxiety for me as I pretty much treat myself.

I made a decision to self treat myself with ferrous fumerate tablets - the packaging states 3 tablets a day (210 mg). I took maximum 1 a day for a month. My GP refused a blood test during a Covid. And two online tests failed. I had to make the best decision at the time. Since starting daily injections 5 months ago, I have experienced 6 day heavy bleeding periods every 28 days. (My early menopause diagnosis has since gone out of the window). 2 months ago after my period I had difficulty getting breath, spooning marks on nails, pale lips and gums and even more fatigue. I was also misinformed that my B12 injections wouldn’t work with low iron. So with little support, considering I have severe neurological symptoms, I made a decision. After a week, l started to feel better.

I have since got a blood test with GP and although asking for iron panel, I only received serum ferritin (20 ug/L). I have another online test here ready to do tomorrow.

I really hope that my 1 month supplementation hasn’t caused damage. Another thing on the worry list (although it’s important you warned about this)

I have saved your reply and will print it for my “PA” notebook!

Wow! ☺️

Scientist's answer...

If you're anaemic due to any cause, but treatment works, then you will incorporate iron into the new cells. 1 mg per 1 ml of red cells. If you've got enough stored then you'll be OK but it will inevitably run down your stores. Your body is very efficient at scavenging iron when breaking down red cells for any reason; iron is scarce, so the design is biased to maintain it! Bleeding is one of the ways we lose iron. There are others [yawn]!

Kerrierach profile image
Kerrierach in reply to FlipperTD

Not a yawn but a yay! It’s so refreshing to get intelligent answers in this site!

It makes sense.

This is all very interesting. So glad there is so much knowledge here! So I’ve been terribly worried about my 21 year old who ignores any and all health issues and recently his labs showed mildly low B12 and high iron. Won’t go for follow up labs until his semester ends because OMG Mom I’m fine...He also has undiagnosed GI issues. So this could be stomach acid issues?

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