ArcaMax

DEAR DR. ROACH: I am 71 years old and was diagnosed with pernicious anemia in October 2024. My B12 and folate levels were low. My antiparietal antibodies were abnormal, but the intrinsic factor antibodies were negative. I received daily B12 injections for six days, and now I'm on them once a month. I'm also taking folate daily.

I still feel really tired and out of breath. The brain fog I had is much better, but I still have tingling in my hands and feet. In a support group I'm a member of, some people are taking B12 injections every other day, but I can't find where this is the standard of care. Can you give me more information about pernicious anemia and the treatment for it? -- M.P.

ANSWER: Pernicious anemia (PA) is an autoimmune disease where the body destroys the cells in the stomach that make intrinsic factor (IF) -- a glycoprotein needed for the efficient absorption of B12.

Without IF, the body needs to get B12 through injection or very high amounts of oral B12. Without B12, the body will often develop anemia and may also develop neurological and psychiatric symptoms. Feeling tired and out of breath are common symptoms of anemia.

The word "pernicious" comes from the time before vitamin B12 was known. There was no specific treatment, although liver and liver extract were used, both of which have high amounts of vitamin B12.

IF antibodies are diagnostic of pernicious anemia, but only about 70% of people with PA will have them. Anti-parietal antibodies can be found in other conditions besides PA, so they do not make the diagnosis alone. However, in a person who has the type of anemia with B12 deficiency and low B12 levels (called "megaloblastic anemia" with unusual white blood cells and very large red cells), the diagnosis of B12 deficiency becomes very likely, especially when symptoms get better with treatment.

However, the anemia with folate deficiency looks exactly like the one with B12 deficiency. Since you have both low folate and B12 levels, treatment with repletion of both nutrients makes sense.

In people with PA and no concerning features, treatment with high-dose oral B12 or injection B12 are both reasonable options. However, people with severe anemia or neuropsychiatric symptoms (like the brain fog and tingling you noted) should be treated aggressively to avoid possibly permanent nerve damage.

This usually means daily injection treatments for a week, then weekly for at least a month, then monthly treatment with injection B12. Once a person has resolved their symptoms, they may also be treated with daily high-dose oral B12 or monthly B12 injections.

These are just guidelines. Some people may benefit from more intensive treatment, and there is very little harm in giving B12. I reassure you, though, that it's likely your symptoms may continue to get better; unfortunately, it is possible that your symptoms may not recover completely. The fact that you are still improving is a very good sign.

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Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to ToYourGoodHealth@med.cornell.edu or send mail to 628 Virginia Dr., Orlando, FL 32803.

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