Please can you help. I am a 34 yo women diagnosed with underactive thyroid nearly 2yrs ago, was started on 200mg levothyroxine & had nearly every side affect. Changed doctors who stopped levothyroxine, retested & told me that thyroid ok. As Im a vegetarian, I asked for my B12 to be tested. Plasma B12 level 424.3 ng/L (180.0-2000.0) is this range normal? Pernicious

Anemia & thyroid problems run through family.

3 Replies

  • Hi,

    I know little about thyroid, so can not help really, just think that if you are not getting treatment for an underactive thyroid , then you will not be well. There is a connection as in if you have autoimmune PA then you can be at risk of more autoimune conditions, underactive thyroid being one of them, and visa versa.

    Perhaps read this, it may help you understand more see:

    I hope this helps,

    Kind regards,


  • Hi,

    Thank you so much for taking the time to reply. The problem I keep coming across is the reluctance of Doctors to thoroughly investigate peoples health problems & they rely on test results. I have been told that the B12 range I have been given is huge & very rare - is this correct?

    Kind Regards,


  • It is different from some labs but nothing wrong with your lab, only good to have such a high range still considered normal! It also depends on what unit is used by your lab.

    Perhaps have a look at this topic:


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