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.
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.
Common signs
- 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
How it's usually treated
- 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
Hashimoto's thyroiditis
The most common cause of an underactive thyroid in the US. The immune system slowly damages the thyroid, so it makes less hormone over time.
Learn more →Type 1 diabetes
The immune system destroys the insulin-making cells in the pancreas, so the body can't make enough insulin to control blood sugar.
Learn more →Vitiligo & alopecia areata
Two autoimmune conditions of the skin and hair. Vitiligo destroys pigment cells, leaving white patches. Alopecia areata attacks hair follicles, causing patchy hair loss.
Learn more →
Wondering if your symptoms fit a pattern?
Dr. Lesher is a naturopathic doctor who specializes in women's autoimmune and chronic conditions. Since 2020, she has helped more than 900 patients overcome and heal from their conditions.