B12 treated but anemia no better

4 months ago I began B12 injections (methyl) for my B12 deficiency with macrocytic anemia. I've been feeling somewhat better, but not 100%. I got results back today from follow-up blood tests and it appears that my anemia markers have not improved at all. I still have high MCH (34; range 27-33), borderline high MCV (99.2; range 80-100) and my red blood cell count has actually dropped (3.66; range 3.8-5.1). I also just discovered that my T3/freeT3 are low (but normal T4/TSH), and have posted to the thyroid forum regarding hypothyroidism. My question is whether one would expect 4 months of B12 injections (every 5 days) to resolve the anemia, or is it just a matter of more time? I would have expected to see a least some improvement in my blood markers, so this is discouraging to see no change. (My folate is and has always been normal.)

14 Replies

  • I take B12 injections myself but am not anemic. I am however hypothyroid. Free T3 is the biggest marker of usable thyroid. If it's low, you may be tired, foggy brain and many other symptoms. My FT3 is low normal and I feel awful. It should be in the upper third of normal to feel your best.

  • Thanks Daisylain! Yes, I suspected I was hypothyroid for a while and it's at least good to have confirmation of low FT3 from my tests. My understanding is that low T3 (with normal TSH) is complicated to treat, since it's typically not caused by dysfunction of the thyroid gland itself, but rather by problems upstream in the pituitary or hypothalamus. How are you treating your hypo?

  • I was sent for a pituitary MRI as my TSH was always normal as well. I take NDT. I do live in Canada and it's typical for doctors to prescribe here. NDT is t4 and T3 from animal glands. A great book to read is "stop the thyroid madness" I am also celiac. Celiac and thyroid often are common together. Even if the hypothyroid is caused by hypo pituitary or a problem in the pituitary axis, you still will need supplemental thyroid. Even if you can fix it, hypothyroid is a long process. It takes time, and low T3 will make you feel awful.

  • This is very helpful. Have you noticed a difference from the NDT? I've never been tested for celiac, but I've noticed I feel much better off grains. Might have to look into that.

  • Definitely Google hypothyroid and gluten. It is very related and many people become gluten free with thyroid issues. When I started NDT I felt about 40% better right away. I am still raising my dose to raise my t3, 10 months later. My doctor wanted me to stay were I was because my tsh was getting low. With the help of everybody on the hypothyroid forum, I learned it's the t3 that counts and tsh can be very low, and will be from the meds. They are an amazing resource.

  • Interesting! But it sounds like celiac is related to hypothyroidism because of the autoimmune connection. So for non-autoimmune causes (like central hypo, caused by pituitary/hypothalamic disorders, which seems to be my case), this wouldn't really apply?

  • Maybe.Once you begin treatment and if you still have symptoms, try a gluten free diet, and see if it helps. It's worth keeping in your mind. I have pituitary issues, and auto immune myself.

  • Try using Hydroxycobalamin you may not be handling the extra methyl very well.


  • The macrocytic anaemia should have cleared in 4 months if you have adequate folate and have been taking B12 for 4 months.

    You could try adding some hydroxo/cyano cobalamin to the mix to see if that makes a difference. Not everyone finds methyl is the best form for them. If that doesn't make a difference then you probably need to start looking for other possible causes of the macrocytosis beyond B12 asorption problems. Not sure what those would be though there may be some issues with actually using and processing B12 and folate that might be involved.

  • If your folate wasn't tested, you may want to find out what that level is. As Gambit says, your anemia should be showing improvement by now. Macrocytic anemia is can be caused by a deficiency in either folate or B12. Since you're getting B12, I would suspect that you're low on folate.

  • Thanks all for your suggestions! My folate is fine and I've been supplementing with methyl-folate, so I'd be surprised if that were the problem. I am going to switch to cyanocobalamin to see if that is more effective than methyl. My understanding is that folate and B12 deficiencies are really the only likely causes of macrocytic anemia, right? So it really should be getting better with methylfolate and the right B12!

  • this article seems to give a pretty comprehensive analysis of the potential causes of macrocytic anaemia


    most of the drug interactions look to me like drugs that are known to interfere with either folate or B12 absorption

  • Wow, this is a great resource. Thanks for sharing!

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