Thyroid UK
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Can B12 injections affect your thyroid?

With my last blood test, my TSH was 4,5 (0,2-4,9) and my free T4 17,9 (9-20,6). I know these my levels are within range, but doesn't TSH seem quite high?

I started B12 injections 5,5 weeks ago (1 injection/week, so already got 5 injections) and my main symptom was anxiety. This anxiety is almost gone, but I have such a depressing feeling, almost all day long, and I didn't have this before injections.

I wonder if this can have something to do with my thyroid? Do the injections affect your thyroid?

2 Replies

thyroid not really my area - more B12 - but people do seem to report that thyroid medication levels needed some adjustments when they start on B12 treatment.

Do you know what your folate levels were like and are like? the need for folate can increase when you start treatment for B12 and there is an overlap - another possibility is that sometimes people actually feel worse before they feel better with B12.

Lots of support on B12 deficiency issues and treatment on the PASoc forum


My folate level was 4,7 (ranges 3,9-26,8), this was before injections started (january)

In july my folate was 10,1, so it dropped quite a bit, even before starting injections.


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