Can I get anemic from too many blood ... - Pernicious Anaemi...

Pernicious Anaemia Society

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Can I get anemic from too many blood tests in a short time ?


Hello !

I have had blood drawn four times in six weeks. My thyroid dr wants another thyroid plus antibodies,, plus renal panel done now.

My ferritin is 56, (15-150)

Iron is 83 (27-139)

Iron Saturation 29 (15-55)

Iron + Bind Cap TIBC 290 (250-450)

UIBC 207 (118-369)

My b12 is out of range...1342 = over range

I complained that i get chills before peeing most of the time lately.

He wants to ck my antibodies again. They were normal.last time on the thyroid.

This was my first visit to this dr, an endocrinologist.

He gave me Metanx samples, which is methylfolate, methylcobalamin and pyridoxal 5 phosphate. Took 3 so far.

I have severe neuropathy. Take no drugs. PCP thinks i have Fibromyalgia and recommended Cymbalta.

Thank you for your help and attention.


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19 Replies

Sounds like you have a good doctor working through the possibilities. Your bloods look okay to me.

I've not come across what you've been prescribed.

Be aware of a fibromyalgia label. They need to keep testing.

You shouldn't get anaemic with the blood tests. Rest.

Hopinggh in reply to Nackapan

Thank you very much !



In answer to the question in the title - 6 sets of blood tests aren't going to cause iron based anaemia - the amount of blood taken is very small in relation to the amount of blood in your body.

Just wondering if you intended to post this on the PAS forum, rather than the TUK form.

If you are supplementing B12 you may want to cut down given that your levels are significantly above normal range.

Hopinggh in reply to Gambit62

Thank you very much !

I thought i was on the anemia community?

The methly forms are not harmful and bioavailable. The amount is 1 mg.of b12 ab

I have neuropathy, so i do need b12. I might have the MTHFR gene, or having trouble with malabsorption . I wasnt tested as to how much of that b12 is bioavailable. ..this gets complicated.

Thank you for your reply!


helvella in reply to Hopinggh

There are many forms of anaemia. This forum is about Pernicious Anaemia which is when people cannot absorb vitamin B12.

I think you are probably referring to iron deficiency anaemia. Unfortunately, I don't think there is an iron deficiency forum on this HealthUnlocked platform.

Hopinggh in reply to helvella

Oh ! Thank you. That makes sense.

I was hoping for anyone, then, for someone with some knowledge in this area.

Thank you so much for explaining that important point.


Gambit62Administrator in reply to Hopinggh

no oral forms of B12 are 'bioavailable' in the sense that they get transferred and used in the cell in the same form as absorbed from food. The process that gets b12 into your cells strips the methyl/hydroxo/cyano/adenosyl element so it can be recombined with which ever of methyl and adenosyl is needed for the specific process it is used for.

MTHFR is a name for the gene that controls the process that adds methyl elements to folate in the cells - there are lots of different variants some have more effect than others and ones that have a really significant effect are quite rare. The effects of variants on processing of B12 is extremely small and in most cases non-existent.

The form of B12 that enables it to be transferred from blood to cells is transcobalamin - where the B12 has been stripped of the methyl/cyano/hydro/adenosyl element and combined with another protein that enables it to pass through the cell wall. B12 bound to transcobalamin generally accounts for about 1/5 of the B12 in your blood so measuring transcobalamin specifically isn't generally necessary - the test has two names - HoloT is used in the states and 'active B12 is used in the UK.

Personally I would avoid any site that tells you that you need to take methyl B12 because it is a 'natural' form - it isn't - its made in vats using microbes as are the other forms and it doesn't make the transfer into cells any easier. People do seem to react differently to different forms of B12 and some even find that taking methyl B12 makes them feel quite ill.

Whilst B12 may not be toxic raising serum B12 levels can affect the way B12 is transported from blood to cells and can make it less efficient - seems to affect about 1/3 of the population - so I would avoid doing it unless there is a specific medical reason, such as a known B12 absorption problem in the gut, or an identified genetic problem with metabolism of B12 in the cell (they occur but they are exgtremely rare).

At best oversupplementing B12 is a waste of time/money. At worst it can have other consequences, though they aren't related to toxicity.

There are many different causes of neuropathy - has a neurologist advised you that you need to take B12?

Nackapan in reply to Gambit62

I find this post very Interesting.

So if raising b12 levels affects the way b12 travels from the blood to the cells and can make it less efficient does this mean there is no going back?

Once b12 raised in the blood the levels have to stay high? Otherwise thers problems of reaching cell level where it is needed?

So over supplementing with b12 can have 'other'consequences' ? Not toxicity though.

I'm sure many are in this bracket

So if you had loading doses and then had regular injections you may have to stay on them whatever? As otherwise you wont get enough to the cells?

So doctors should never just stop them or Indeed reduce them.

So 2/3 of people having had high doses of b12 can process it efficiently again if its possible depending on the initial reason for deficiency?

So the more you have to get well the more you need?

Thanks in advance if you can clarify if I've understood correctly

fbirder in reply to Nackapan

"So if raising b12 levels affects the way b12 travels from the blood to the cells and can make it less efficient". There is no evidence for this.

Nackapan in reply to fbirder

Oh okay . Thanks

Gambit62Administrator in reply to Nackapan

Nackapan - this doesn't affect everyone - but if it does then the individual concerned is going to need to maintain higher B12 levels than normal and that may be part of the reason why some people need much higher levels of B12 post loading shots to function, but exactly why higher levels are needed by some isn't fully understoood. The ways cells work really isn't fully understood, particularly in relation to how variations in the many genes that code the processes that go on in cells. There is at least one report of someone who had neuropathy caused by B12 deficiency but post loading shots had very high B12 levels but couldn't function without extremely frequent shots that kept levels much higer than normal which is my justification for believing it is about efficiency of transfer from blood to cells.

It should also be noted that one of the symptoms of conditions that can cause serum B12 levels to be raised is functional B12 deficiency - ie all the symptoms of B12 deficiency despite high serum B12 - I don't know if there have ever been any studies of trying to treat the functional B12 deficiency in these patients with injections as it would seem to make more sense in these cases to treat the cause of the raised B12.

Hopinggh in reply to Gambit62

Thank you very much.

Yes, my endocrinologist gave me Metanx samples and said we can get a prescription for it later. It has a higher amount of B6, which could be a reason he gave it to me because i complained of being extremely tired. He said take this and see if you feel better. He did not give me any lengthy explanations.

I am not taking any other B 12 . I used to take high dose b12 multivitamins for years.

What im also concerned about is having read several articles stating various serious reasons there are for over the limits B12 readings such as liver problems, leukemia and cancer. Also reading some doctors advise to stop supplenenting b12 to see if it goes down. Some people said it did not go down and also people have said that some drs seem to disregard it as a problem. Contrary info makes this confusing.

For now, i will be checking it in two months and hope it went down.

Reason for my neuropathy is undetermined. I am not diabetic.

Thank you, again. You are very kind.


Gambit62Administrator in reply to Hopinggh

there are many reasons for neuropathy - B12 deficiency and diabetes are just two.

In some people it can take years for B12 levels to drop once raised - that comes out of very early studies of using B12 supplements - there is a great deal of variation on how long it takes for B12 to be removed. There are tests for other causes of raised B12 and I am sure your endo will have looked into them - if you are worried then I would suggest you raise your concerns with him.

Hopinggh in reply to Gambit62

Thank you !

I did not know it can take years to drop .

I had only one televisit PCP and one endocrinologist visit. I will be sure to be questioning them.

Thanks so much, again.


Litatamon in reply to Gambit62

"At best oversupplementing B12 is a waste of time., **At worst it can have other consequences**, though they aren't related to toxicity."

Starred section of your answer - what is it referring to, Gambit?

Gambit62Administrator in reply to Litatamon

Litatamon, a) it makes obtaining a diagnosis of a B12 absorption problem more difficult and b) raised serum B12 can result in functional B12 deficiency - though it does appear that that can be treated by raising B12 levels higher - or, in the case of patients who have been treated with B12 injections for an absorption problem, be resolved by keeping B12 levels high.

Litatamon in reply to Gambit62

Thank you.

Referring to b -

I was curious because it seems very circular in nature. One is following the every other day until no more progress seen. And then the serum value sits very high. So then you've created a functional deficiency by having consistently raised serum levels? Is that correct? I guess I don't get an alternate choice when serum raising injections keep symptoms at bay.

Gambit62Administrator in reply to Litatamon

you may not have functional B12 deficiency - just that high serum B12 seems to be a condition that may trigger functional B12 deficiency - in the same way that eating a diet full of highly processed foods may trigger diabetes. Its statistics rather causality, which points to causality of some sort but not there are obviously some other things going on in the background, eg genetics.

Yes it is very circular if you do respond to high serum B12 in that way - but it does seem to be like a damn - holds the water back but if the water levels rise enough the water trickles over the top.

There may also be other things going on - and it underlines the problem of using serum B12 as a test to management any absorption condition post injections. You do need to go by symptoms.


All...below, a paper that may provide further's a very interesting read.

The posted extract from the paper linked below suggests that high levels of serum B12 may (in rare individuals) cause an autoimmune-immune reaction that produces TCB 11 auto-antibodies that can potentially cause a decline in B12s ability to attach to Transcobalamin 11 ... and thus impact on B12 delivery to the cells.

'Contrary to vitamin B12 deficiency, the patho- physiology and clinical consequences of high serum cobalamin have, until now, been very little studied. It is however currently considered that an increase in plasma levels of vitamin B12 may be an indicator of a functional deficit with clinical conse- quences paradoxically similar to those of vitamin B12 deficiency. Indeed, an increase in the binding of vitamin B12 to HCs, secondary to an elevation in their plasma levels (especially for TCB I and III which are by far the majority), leads to a potential decline in its attachment to TCB II and therefore alters its delivery to the cells. Thus, a functional deficit in vitamin B12 with an increase in homocysteine and/or methylmalonic acid levels can occur, even though the initial anomaly in this instance is not a serum B12 deficiency'.

Whilst this paper is essentially concerned with raised B12 due to disease entities (I.e. liver disease, cancer et al), it nevertheless speaks to the fact that high serum B12 levels can set-off an autoimmune reaction to TCB 11 which may result in functional B12 deficiency due to altered B12 delivery to the cells. logical implication, if raised serum B12 levels can have this effect...then this effect can also potentially arise when serum B12 levels are artificially raised by injection (though this is quite rare).

But of course, when B12 deficiency is present it needs to be treated....and treatment with sufficient B12 to keep symptoms at bay and effect neurological repair (where neurological symptoms are present) is, as we all know, essential


When functional B12 deficiency is present then the solution appears to be to give more B12 (though nobody really seems to know the mechanism by which this works - very little research on this currently).

Also - here's a paper from a practising haematologist that advises that there is no reason to advise against self-injection / more frequent B12 injections (than the one-size-fits-all regime currently 'allows' (ha). (Haematologist B12 Treatment Review March 2017 – Includes Advice No Reason to Advise Against Self-Injection/More Frequent B12 Injections)

Hopinggh - I'm sorry that your post has gone way off-topic but hope that you’re now reassured that your blood tests won't have caused you to become anaemia (if you think about blood donors, the give a whole bag (about 500mls), much more then collected for blood tests, with no ill effect).

I'm turning off replying to this post because it’s strayed way-off topic but please be assured that this is not because there’s anything 'wrong' with your post. It's to save you potentially receiving notifications for replies that don't actually have anything to do with the question you ask. Please do put up new posts if you have any questions or need more advice 🙂.

All - hope the posted papers help to further understanding on some of the issues discussed.


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