In autoimmune gastritis (AIG) or thyrogastric syndrome (new one to me), iron deficiency may come before B12/cobalamin deficiency. Iron levels may need to be monitored, but AIG patients have difficulty with supplements and could need infusions. Iron deficiency + thyroid problem may be a signal for the gastric condition that will create pernicious anemia. Pernicious anemia is the end stage. I hope this helps with recent comments about not giving treatment until the B12 anemia shows. Below, I will try to give the web link but in case it doesn't work, also the article.
Toh, B.H. (2014) Diagnosis and classification of Autoimmune Gastritis. Autoimmune Review 13(4-5). ncbi.nlm.nih.gov/pubmed/244....
Cellini, H. et al (2017). Hashimoto's thyroiditis and autoimmune gastritis. Front. Endocrinol 8 (92). (Lausanne). ncbi.nlm.nih.gov/pmc/articl....
Goncalves et al. (2014). AIG presenting as iron deficiency in children. World Journal Gastroenterology 20(42). ncbi.nlm.nih.gov/pmc/articl...
B12 and iron deficiency link?
A clinical picture of a B12 deficiency and PA explained.........
Examining the Diagnosis and Treatment Experiences of People Living With Autoimmune Gastritis and Pernicious Anemia
Iron Deficiency and PA
Signs of B12 deficiency in the mouth
