As Clutter has already indicated, MCH is elevated in B12def. and your symptoms suggest this might be so, especially as autoimmune thyroid disease and PA/B12 are often interlinked. Have you been supplementing with B12? ***In any case, the serum B12 is only an indication of levels in the blood and not in the tissues, so you can still be deficient if you have a problem with absorption.
The following is a helpful link with lots of advice and information, with templates for writing to your doctor, as well as an excellent film:
Latest BMJ Research Document with summary re. tests, diagnosis and treatment:
Cmim/BMJ document. " Summary:
* Vitamin B12 deficiency is a common but serious condition
* Clinical presentation may not be obvious thus leading to complex issues around diagnosis and treatment.
* There is no ideal test to define deficiency and therefore the clinical condition of the patient is of utmost importance."
* There is evidence that new techniques, such as measurement of holotranscobalamin and methylmalonic acid levels seem useful in more accurately defining deficiency.
* If clinical features suggest deficiency, then it is important to treat patients to avoid neurological impairment even if there may be discordance between test results and clinical features.
Severe deficiency shows evidence of bone marrow suppression, clear evidence of
neurological features and risk of cardiomyopathy.
It is important to recognise that clinical features of deficiency can manifest without anaemia and ***also without low serum vitamin B12 levels. In these cases, treatment should still be given without delay."