Pernicious anemia
Autoimmune gastritis
Autoimmune conditionThe immune system attacks cells in the stomach lining that make intrinsic factor, a protein needed to absorb vitamin B12.
For education only — this guide can't diagnose you. If these signs sound familiar, talk with a healthcare provider. Book a consult
What happens
Without intrinsic factor, B12 can't be absorbed from food, even with a good diet. Over time, low B12 causes anemia with large red blood cells and can damage nerves. The same attack lowers stomach acid, which can also reduce iron absorption.
Who gets it
It's more common in women and in people over 60, and more likely in people with autoimmune thyroid disease, type 1 diabetes, or vitiligo.
Signs worth getting checked
- Fatigue, weakness, or shortness of breath
- Pale or slightly yellow skin
- Numbness or tingling in the hands and feet
- Balance problems
- Memory problems, brain fog, or low mood
- A sore, red, smooth tongue
- Indigestion or feeling full quickly
Labs to ask about
- Complete blood count (including MCV, the size of red blood cells)
- Vitamin B12 with methylmalonic acid (MMA) or homocysteine
- Intrinsic factor antibodies and parietal cell antibodies
- Ferritin
Treatments your doctor may discuss
- Lifelong B12, usually by injection or high-dose oral B12 as your provider advises
- Checking for and treating iron deficiency
- Periodic endoscopy for some people, since autoimmune gastritis raises the risk of certain stomach growths
Supportive steps to discuss with your provider
- Ask for MMA if your B12 is borderline. A B12 level alone can miss a deficiency.
- Don't treat anemia with folic acid alone. It can hide a B12 deficiency while nerve damage continues.
- Ask about B12 if you take metformin or acid-reducing medicine long term.
See a doctor promptly if you have
- Numbness, weakness, or an unsteady walk
- Shortness of breath or chest pain
- Confusion or memory changes
- Black stools
Related conditions
Ready to find the root cause?
Dr. Lesher is a Naturopathic Doctor who focuses on autoimmune and chronic conditions in women. Since 2020, she's helped hundreds of patients stop managing symptoms and start healing.