B12 is a vitamin which has a key role in red blood cell metabolism of your entire body, giving you energy, sharpness in your brain, and healthy nervous system functioning.

And unfortunately, a certain percentage of hypothyroid patients have low levels of this important vitamin. That deficiency is largely due to years of digestive issues common with hypothyroidism, whether one is either undiagnosed due to the lousy TSH lab test, or under~treated on T4 meds like Synthroid, Levoxyl, Levothyroxine, Eltroxin, etc.
http://www.stopthethyroidmadness.com/b12/

Vitamin B-12 and your thyroid gland are both essential to your metabolism. Vitamin B-12 works in conjunction with other B vitamins, and are considered to be part of the vitamin B complex. These vitamins have a role in the metabolism within every single cell. A deficiency of vitamin B-12 can alter this process. Hypothyroidism, a condition associated with inadequate thyroid hormones can also disrupt the metabolic process.


Read more: http://www.livestrong.com/article/48...#ixzz2JXVq8ieh
I looked at the symptoms of low B12 and there are MANY. I had brain fog, poor memory, poor concentration, extreme tiredness, blurred vision, nerve pain in my upper arms and felt suicidal.
http://www.thyroiduk.org.uk/tuk/get_...udies/B12.html

B12

People with an underactive thyroid or people with no thyroid cannot absorb this vitamin. A serious lack of B12 can cause mental illness, various neurological disorders, neuralgia, neuritis and bursitis. Some doctors believe the "normal range" of B12 is too low and that the normal range should be at least 500 - 1,300pg/ml (rather than 200 - 1,100).
http://www.thyroiduk.org.uk/tuk/treatment/vitamins.html


I Norge mener legene at en B12 på 240 er helt ok. I USA eller Japan ville du fått sprøyter