Ask the doctor: Why do I need shots for low vitamin B12?

Vitamin B12 levels that are too low increase your risk of nerve damage and anemia—a lower than normal number of red blood cells. What is "normal" can vary according to the test and laboratory. In our lab, the lower normal limit of vitamin B12 is 180 picograms per milliliter (pg/ml) and the normal range is 180–918 pg/ml. In a recent case series of people with low B12 levels, only 29% of them had anemia. So your situation isn't all that unusual.
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