Elevated B12

I have recently had my routine blood word. He also did a B12 and D3 test. My B12 came back high at 1600. He rechecked it 10 days later and it was the same. I have Hashimoto's Thyroiditis and Mast Cell Activation Disorder. I know a high level can be caused by blood diseases and tumors but was wondering if it could be caused by my Hashimoto's or the MCAD or something less benign.

Thank you!

15 Replies

  • Are you supplementing vitamin B12?

  • No I have not supplemented b12 in over a year.

  • When you did supplement B12 were you supplementing at high levels? If you were you could have elevated B12 levels for a very long time because the body stores it in the liver. I have read that a couple of years worth (at least) is stored in the liver.

  • I only supplemented with a multivitamin. I had a test for B12 about a year ago and it was 650.

  • You could ask for advice on the pernicious anaemia society community :


  • Did you also take vitamin B complex with the B12?

    Shortage of another Vitamin B can mean the other B's don't get used either. They apparently all need to work together.

    My own experience I have had in recent past slightly above range raised B12 & very high folate (Which was worrying me as I had never supplemented)

    But recently, starting supplementing vitamin D, this soon caused/revealed low B5. (Peripheral neuropathy) Starting a good vitamin B complex, (improving the low B5), I then found the B12 & folate fell rapidly (now actually supplementing b12)

    This website explains the link between vitamin D & vitamin B


    "Usually within the first year of vitamin D supplementation the B5 body stores get used up and new symptoms of pain, burning and balance difficulties begin. Patients who have fibromyalgia or arthritis or autoimmune disease are already severely B5 deficient even before their vitamin D deficiency is detected."

  • Thank you SlowDragon. I do have Hashimoto's so it could be the autoimmune aspect! Thanks for the link! I'll check that out immediately.

  • Also do you have low vitamin D?

  • I have normal vit D but have taken a supplement. My blood work is all normal. Liver enzymes, kidney function and complete blood count normal.

  • It's good news that your liver enzymes are normal - if they weren't it would be worth having a scan of your liver. It is unusual and probably worth keeping an eye on though. Perhaps have your liver function tests repeated in a few months?

  • My GP has decided to send me to a hematologist to check for some sort of blood disorder but does not feel that he will find anything. I have had a rough year! Been diagnosed with asthma, sleep apnea and MCAD. Had a cardiac catherization yesterday but all my coronary arteries were completely open, Praise God!

    I've been on several rounds of steroids due to bad itching from the MCAD and from sinus issues. Thank you so much for your responses! If you think of something else please let me know. My system has just out of balance all year long!

  • Poor you, that does sound rough x

    Do you know if your Hashimoto's is being treated effectively? I had to look up MCAD to see what it was and see that thyroid disorders can mimic the symptoms of MCAD. Just made me wonder whether it really was MCAD or whether they simply haven't put you on enough (any??) thyroxine. You may have already seen this: jhoonline.biomedcentral.com...

  • You could be exactly right! I have had problems with my thyroid. I itch when I take the usual drugs like synthroid and armour thyroid. I am taking cytomel only which is the T3. I know I would feel better if I could take the correct drugs.

    Can't tell you how much I appreciate the support!!!

  • kdr,

    Welcome to our forum.

    It is possible to have a high Vit B12 blood circulation but still be deficient as the serum blood test measures the total amount which includes holohaptocorrin, the inactive form of B12.

    You could ask your GP to measure MMA (Methylmalonic Acid) and Homocysteine as high levels may determine low active B12 levels. Also elevated homocysteine may disrupt thyroid metabolism at the cellular level as it blocks T3 from binding with enzymes.

    In the stomach, cells called parietal cells secrete hydrochloric acid (Hal) located in the stomachs lining allow us to digest and absorb our food. They also produce intrinsic factor which allows us to absorb vitamin B12 and folic acid. Failing adrenal glands (used by low thyroid hormone or meds not working right) inhibits our ability to produce acid.

    If you have gut issues you could ask your GP for a Intrinsic Factor and Parietal cell Antibodies test. Also a low iron level may skew serum B12 results (by altering the size of red blood cells) as will supplementing B12 by falsely elevating levels.

    Many people with Hashi appear to have a polymorphism on their MTHFR gene meaning they can't convert & excrete B12 in the usual way. This may also predispose them to mast cell disease as 5-MTHF regulates biosynthesis of BH4 (tetrahydrobiopterin) and a deficiency increases mast cell degranulation (possibly encouraged by Hashi stuff too).. Inadequate BH4 formation will also affect the neurotransmitters: dopamine, norepinephrine, serotonin and melatonin.

    There is an ACTIVE B12 test that your GP probably won't know about ( aka holotranscobalamin) test (HoloTC), which only measures the amount that is usable at cell level. The test is available on the NHS at St Thomas' Hospital but requires a GP's referral. It is also available from private labs (link below).

    Have you had folate (which works with B12), Ferritin and Vit D tested ? ? ....

    Have you performed any adrenal saliva stress tests to identify cortisol issues ? ? ..

    Post any results complete with ranges (numbers in brackets) for members to comment.


    Active B12 test



    Tetrahydrobiopterin deficiency


  • I have not had any adrenal saliva test. My ferritin level is 155.4 (15-200) Vit D is 41. (30-100). B12 is 1568 (239-1050) Tryptase 5 (<11). All you other tests were normal except for my blood sugar. It was 200 but I'm hoping it is because I was on prednisone when it was checked. My liver and kidney functions are all within normal limits. I am taking T3 only for my thyroid because I itch terribly with synthroid and armour thyroid.

    Thank you for any advice you can give me!

You may also like...