Pernicious anemia is a condition in which the body can't make enough healthy red blood cells because it doesn't have enough vitamin B12. Vitamin B12 is a nutrient found in some foods. The body needs this nutrient to make healthy red blood cells and to keep its nervous system working properly.
People who have pernicious anemia can't absorb enough vitamin B12 from food. As a result, the stomach stops making intrinsic factor which is a protein made in the stomach. In pernicious anemia, the body makes antibodies that attack and destroy the cells that line the stomach and make intrinsic factor. Why this autoimmune response occurs is unknown. Without intrinsic factor, a body can't move vitamin B12 through the small intestine, where it's absorbed. This leads to vitamin B12 deficiency.
Vitamin B12 deficiency can result in general symptoms of anemia as well as nerve problems. These may include weakness or fatigue, lack of energy, or numbness and tingling that start first in the hands and feet. Additional symptoms may include muscle weakness, slow reflexes, loss of balance and unsteady walking. Severe cases can lead to confusion, memory loss, depression, and/or dementia.
The term “pernicious” means “deadly.” The condition is called pernicious anemia because it often was fatal in the past, before vitamin B12 treatments were available. Currently, pernicious anemia usually is easy to treat with vitamin B12 pills or shots. With ongoing care and proper treatment, most people who have pernicious anemia can recover, feel well, and live normal lives.
Pernicious anemia is more common in people of Northern European and African descent than in other ethnic groups. Older people also are at higher risk for the condition. This is mainly due to a lack of stomach acid and intrinsic factor, which prevents the small intestine from absorbing vitamin B12. As people grow older, they tend to make less stomach acid.