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Thyroid UK
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Raised B12

My daughter had recent blood tests that showed her B12 at 1200 ( range 191 - 663). This was also at this level 2 years ago. She has not been taking Vit B supplements.

She has Down's Syndrome and also has Hashimoto's Thyroiditis.

I would be grateful for any help or advice. Her GP is unconcerned but has been so about TSH in double figures, so no surprise there.

7 Replies

Has your daughter had recent full blood count, liver and kidney function blood tests? If so are all the results within range?


Thanks for your reply bluebug and apologies for not having had the chance to come back to you.

Recent FBC and liver tests were ok. Not sure if any kidney function tests have been done.



The trouble with the B12 blood serum test is it only measures the amount of B12 in the blood stream and not the active amount being utilised.

Vitamin B-12 can only be absorbed in the small intestine and due to intestinal ailments common in Hashi sufferers, many with high levels may not be able to absorb it in their gut. Vit B12 is released for absorption by the activity of hydrochloric acid and protease, an enzyme in the stomach and supplementing Betaine HCI with Pepsin and digestive enzymes may help with absorption if there are any gut issues.

GP do not understand Hashimotos or the possible accompanying genetic impairments and subsequent deficiencies that stop us working so well. You could test her active levels with the active (holotranscobalamin) B12 test (HoloTC) measuring only the active Vit B12. This is available on the National Health at St Thomas’ Hospital, London with a referral from your GP.

Alternatively, measuring MMA (Methylmalonic Acid) and Homocysteine on the National Health can be useful as high levels may determine low B12. Intrinsic Factor and Parietal Cell Antibodies will highlight an inability to absorb B12 via the gut and also give Folate status.

High serum B12 that can not be used properly by the cells will be exported back to the blood where it binds to haptocorrin. This is then imported by the liver and recycled via bile to the gut (salvage and recycle pathway for B12). This B12 will be unusable to the bodies cells making you "deficit in B12 with a high serum level reading" and create harder work for the liver..

... BUT if your daughter is utilising all the Vit B12 well, according to PA Society, Vit B12 is optimal at 1000 so your daughter is not a lot over as any excess is pee'd out.

A TSH in double figures does not sound good unless it was double in minus figures .... which I suspect NOT ! ....


Vit B12 Active Testing.



Thanks for your reply Radd and apologies for not having had the chance to get back to you sooner.

You say about Hashimoto's and possible genetic impairments and subsequent deficiences - what could these be?

We would not be able to get our daughter to London. So can she be tested for MMA / Homocysteine / Intrinsic Factor and Parietal Cell Antibodies on the NHS anywhere? ( incidentally, a recent Folate test showed 9.9 - range 3.8 - 16 )

Double figures TSH was some time ago and this year TSH has been ok at under 2.0. However despite this, my daughter has no energy, is constantly tired and is depressed and often anxious. These are conditions she never used to have.

I would greatly appreciate any further advice you may have.



Many Hashimoto sufferers (including myself ) suffer MTHFR genetic impairments.

The possible ramifications are huge and can effect thyroid function but put simply this means we have difficulty breaking down folate vitamins (of which folic acid is the precursor to), which can cause high homocysteine (increasing risk of coronary heart disease & BP conditions).

Elevated homocysteine will be poorly converted to glutathione (chief antioxidant and detoxifier) making us more susceptible to stress and toxin buildup. ( I had all amalgam removed last year.) It will also convert less to methionine increasing risk of arteriosclerosis, fatty liver degenerative disease, increasing free radical damage… and produce less SAM-e which can increase depression.

We also end up with possible elevated folate (folic acid) and Vit B12 as have the problems of converting inactive to active, so it simply builds up in the blood stream.

Genes are passed down by Mum & Dad and there are many different mutations but two that are most commonly problematic. Obviously you can’t change a defective gene but you can help it do its job better and minimize problems. Avoid foods with added folic acid such as cereals, pasta, rice, flour and other grains.

Your daughters folate result looks OK but the best way to measure folate is a blood Red Cell Folate test. Some doctors know about this & some don't. My endo requested my GP to conduct this but GP couldn't find it on his list. However, other members have had better success. Otherwise use private labs - link below.

I understand Homocysteine & MMA can be easily tested by your GP. I don't know about Intrinsic Factor and Parietal Cell Antibodies. You will have to ask.

Although available on the National Health, the Active Vit B12 isn't widely known about by doctors yet but is available through private labs - link below.

There is also another common mutation on the CBS gene. This converts homocysteine into cystathionine, and removes sulfur containing amino acids. When impaired it can cause an excess of sulphur and low serotonin//dopamine, and chemical sensitivity.

Sometimes just performing a liver cleanse will helps get things working better and of course addressing any gut issues ( candida, IBS, etc).

I don't think it essential to have the genetic testing but just to be aware of the possible deficiencies (with//without elevated levels) and the consequences if a deficiency were to be supplemented incorrectly. Folate works with B12 to help create and regenerate red blood cells. Deficiencies in either can cause similar symptoms and they can be supplemented as Methylfolate and Methylcobalamin together with a B Complex.

A TSH in double figures could be accountable for your daughter feeling so unwell. If you have recent thyoid hormone blood test results, post (as a new question) complete with ranges (numbers in brackets) for members to comment.

The T3 result is the important one as being the "active" hormone, gives us wellbeing. GP's are not always allowed to test T3 ( down to cost) so members use private labs -link below.





Active B12 Test Info



Active Vit B12 & Red Cell Folate Test



Private labs


1 like

Thanks for your reply Radd - lots of info. and much to think about.

TSH was in double figures last year and probably due to Setraline ( SSRI ). After Setraline was stopped the TSH has been less than 2 and T3 usually around 6.

Very many thanks for your help and advice


Hi scood, it could be malabsorption as radd suggests. My levels were high too at 1099 without the benefit of feeling any better for it.


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