Pernicious Anemia and B12 Injections

Q:  I became anemic when my daughter was born in 1940. When I was finally diagnosed with having pernicious anemia (PA), I was 29 years old. My daughter also has P.A. It was diagnosed when she was 48.

I have been on B12 many years - I am now almost 80. I receive monthly B12 injections, and would like to know if I still need these every month? My doctors don't check on the need as with other medication

A:  If you were diagnosed with PA at such a young age, chances are you need the B12 replacement now, at the age of 80, more than ever. In a survey of 548 older people, ages 67-96, about 20% had low levels of B12 on blood tests. Only half of those people were actually anemic, so they and their doctors were probably unaware of the B12 deficiency. Adequate B12 is important for other reasons than just prevention of anemia. The nervous system also utilizes B12, so a lack of B12 can result in numbness and tingling of the hands and feet, memory loss, disorientation, depression, and even personality change.

Older people may have lower levels of B12 because they do not adequately absorb B12 from their food. Once malabsorption starts, the person will become deficient in one to two years. The best way to replace B12 is through injections. Pills are available but would not be absorbed any better than B12 in food unless given in fairly high doses. The usual dose is 1 mg per month given by injection. Ask your doctor to measure your blood level of B12. Most likely you will continue to require a monthly shot

"Dear Doctor" is a compilation of patient questions answered by doctors from the Medical College of Wisconsin.