Just been to GP for blood test results .I have Hashimotos, and had radioactive iodine done to destry my thyroid before full Levo replacement but since my dose was reduced from 125mcg to 100 mcg I now feeling increasingly very tired , cold hands, etc , or wondered if I was now underdosed, or anaemic. However since my haeoglobin result was 135gl could it be something to do with my Vit B 12 level which seems low at 353 ngl,( the parameters for Vit B 12 in the local lab are 200-940 ng/l.) Is it this that is causing my symptons as I understand that Vit B 12 is involved in T 3/ T4 metabolism. Should I be supplementing, with Vit B 12, and if so, by how much? Hope someone can shed some light!