High B12 low Ferritin

[Monika53]

Latest blood test shows high B12 of 1537 ng/L (197-771) and low ferritin 17 ug/L (30-400) GP prescribed iron tablets but no concern raised re B12. I do supplement both but stopped 5 days before blood tests. Is the high B12 worrying/ should I stop supplementing? I am on t3 only and that shows as 5.7 pmol/L ( 3.70 -6.70). Many thanks for any help

[SeasideSusie Remembering]

Monika53

Are you taking sublingual B12 or injections?

You need to stop iron 7 days before any iron tests and the test should be done after a 12 hour fast.

[Monika53 in reply to SeasideSusie]

Thank you for your speedy response. I was taking sublingual b12 and liquid iron but forgot to stop 7 days before so did just 5 days. I did fast though although GP insists you don’t need to.

[SeasideSusie Remembering in reply to Monika53]

Monika53

In that case I would say that you no longer need to supplement with B12. I'd leave it off for 4-5 months then retest, this will give a baseline to see what you are holding on to.

When taking B12, we need a B Complex as well to keep all the B vitamins in balance. Have you been taking a B Complex? If so, did you leave it off for 7 days before the test?

Were you supplementing with iron before this test? How much? If so a ferritin level of 17 is dire. Have you also had an iron panel and full blood count done?

[Monika53 in reply to SeasideSusie]

Hi Susie , yes I am taking a B complex too and spatone liquid iron. Only other iron panel that shows is folate as normal - no range given. Can’t see another full blood count but the results may not all be up yet. I have tel consultation with GP on Friday and will need haemorrhoids investigated , so may be reason for iron ? Thank you for all the support you give.

[SeasideSusie Remembering in reply to Monika53]

Monika53

Folate is not part of the iron panel, it's usually coupled with B12.

Iron panel consists of Ferritin, Serum Iron, Transferrin Saturation percentage, Total Iron Binding Capacity (or Transferrin).

When Ferritin alone tested and it comes back low, it can be an indication of iron deficiency or iron deficiency anaemia. The iron panel will show if you have iron deficiency and the full blood count will show if you have anaemia. In either of these cases the GP should prescribe the necessary iron and monitor regularly.

Did you leave the B Complex off for 7 days before the test? This is necessary before any blood test because it contains Biotin, and if Biotin is used in the testing procedure (which most labs do) then it gives false results if you continue taking it.

[Monika53 in reply to SeasideSusie]

I only stopped all supplements for 5 days so maybe the reason the results are a bit off? I usually stop everything for 10 days and t3 24hrs. I’ll stop the b12 and ask for a retest in a few months. If any more results come through online I’ll add them here. Many thanks Susie

[SeasideSusie Remembering in reply to Monika53]

Last dose of T3 should be 8-12 hours before blood draw, splitting dose and adjusting time the day before if necessary. Taking T3 too close to blood draw gives a false high FT3, taking it 24 hours from blood draw gives a false low FT3 and may lead to overmedication if you adjust dose based on those results.

5 days is probably enough to leave off the iron and B Complex to not make any difference.

[SlowDragon Administrator]

Looking at previous posts you take very high dose T3?

Was blood test done with last third of daily T3 dose at roughly 8-12 hours before test?

When were vitamin D and folate levels last tested

[Monika53 in reply to SlowDragon]

Hi Slow Dragon, thank you for your response. I have been reducing my T3 gradually as I have found it hard to find a reputable supplier, and have halved my dose so far. This has led to severe constipation and aggravating existing hemorrhoids. VitD was 97 and serum folate 13.4 both in March 2018 . Folate Range was 4.6- 18.7 in Aug 2016 but they haven’t provided a range since then.

[Thenightowl]

I wouldn't worry about your b12, there is no known upper dangerous limit and the body excretes any excess. My serum b12 was over 2000 before I started daily injections, raised with sublinguals. B12 testing is skewed for at least 4 months after supplements. It was previously repeatedly low.

Have you ever had a low/lowish b12 test when not a strict vegan?

[Monika53 in reply to Thenightowl]

Thanks for your reply - level always been in ‘normal’ range before. I’ll see what GP says on Friday !

[CMS23]

Hello Monika, I joined this site because I just came across your question from two years ago. I'm in the USA and saw my hematologist today. I also had really high serum B12 and very low ferritin. After that, I was tested and positive for Intrinsic Factor antibodies which resulted in a diagnosis of Pernicious Anemia.

My hematologist explained to me today that the very high serum B12 with low ferritin means that there's a strong suspicion of pernicious anemia, and that a patient must be checked for Intrinsic Factor antibodies (and also for antiparietal cell antibodies). (I didn't understand that when I was diagnosed in 2021, but we discussed my old lab values today.)

So maybe you've already been tested since you posted a long time ago, but I felt like I must come and post here in case you haven't yet been checked for P.A.

[Monika53 in reply to CMS23]

Thank you so much for taking the trouble to respond. I can’t see results of all the tests that have been done but I have iron clinic on Thursday so will ask them to check if those tests have been done- blood test in December 2021 was normal B12 but low ferritin.

[Loiss in reply to CMS23]

hi there, did you glean any further understanding of low ferritin with high b12? I’m at the beginning of this journey and focus is on low ferritin. No one concerned about high b12.

[CMS23 in reply to Loiss]

Yes, I also learned that the presence of intrinsic factor antibodies in the serum can skew the results of the serum B12 test, to give a falsely normal or even a very elevated result. Here is a link about this from The American Society of Hematology:

ashpublications.org/blood/a...

** A patient can have B12 neurological deficiency symptoms and inadequate B12 absorption and show normal lab results: "Extremely high-titer IFAs [intrinsic factor antibodies] have been reported to cause in vitro interference by binding the test reagent, leading to falsely normal or even high B12 levels."

The link goes on to say that the patient's first serum B12 result was 1328, but when a second lab took measures to reduce the IFA interference in the serum, the patient's actual serum B12 was only (a shockingly) 65. (But the IFA test is said to be consistently reliable.)

One other thing: MCV can be elevated with B12 deficiency, but low ferritin can lower MCV. So if a person has both going on at the same time, MCV can look completely normal.

[Loiss in reply to CMS23]

thank you so much 🙏 I’ll speak to my doctor about this.

[CMS23]

You're welcome, Monika! That's great that you're going the clinic on Thursday. I think most doctors in the USA don't even realize that an excessively high serum B12 result is a problem when there is low ferritin! My rheumatologist ordered the test for the Intrinsic Factor antibodies for a completely different reason.

But the hematologist yesterday said that those two results together (high B12/low ferritin) mean that I.F. antibodies must be checked (even though that's not the reason my rheumatologist ordered the test). Something about those I.F. antibodies in some way interfering with the serum B12 result and making it very high. (I don't completely understand that yet.)

My hematologist also said that Antiparietal Cell Antibodies must be checked at the same time because their presence will confirm some kind of autoimmune gastritis that's also related to B12 absorption. And, if present, those antibodies, like the I.F. antibodies, also interfere and give a really high serum B12 result.

She also mentioned that the presence of I.F. antibodies (meaning a diagnosis of P.A.) is more common than the presence of Antiparietal Cell Antibodies (meaning a diagnosis of autoimmune gastritis), but that either of them is a possibility.

I hope you get some good answers on Thursday!

[Spreadlove8 in reply to CMS23]

Hello, I have exactly the same issue: elevated B12 without any supplementation and low ferritin. I have many neurological symptoms, but the doctors aren't helping, and no one has suggested testing for pernicious anemia. Could you please tell me if you experienced any neurological symptoms? If so, have they disappeared? What treatments were you offered? Thank you very much.