Vitamin B12 belongs to a group of water-soluble vitamins called B complex. Vitamin B12 plays a role in proper red blood cell production, nervous system health and DNA synthesis, according to the Office of Dietary Supplements. A deficiency of vitamin B12 can lead to pernicious anemia, a blood disorder characterized by a lack of healthy red blood cells in the body.
Physiology
In order to properly absorb vitamin B12, the body requires a protein called intrinsic factor, which is produced by the parietal cells in the stomach. When vitamin B12 enters the body, it must bind to intrinsic factor in order to be absorbed by the intestines. Once the vitamin is absorbed, it can successfully enter the bloodstream.
Causes
A lack of intrinsic factor is a leading cause of pernicious anemia. Some people are born without the protein, but it most cases, a lack of intrinsic factor occurs as a result of an autoimmune diseases or stomach surgery. Occasionally, pernicious anemia develops because the small intestine cannot properly absorb vitamin B12. Malabsorption in the small intestine may be caused by digestive diseases, certain medications, excess production of bacteria or surgical removal of all or part of the small intestine. In a small number of cases, pernicious anemia develops because of a lack of vitamin B12 in the diet. According to the National Heart, Lung and Blood Institute, this is more common in strict vegetarians and vegans since animal products are the best sources of the vitamin.
Symptoms
Common symptoms of pernicious anemia include fatigue, dizziness, shortness of breath, coldness in the hands and feet, paleness in the skin and gums, nausea, vomiting, diarrhea, loss of appetite and weight loss. Pernicious anemia can also result in heart palpitations or heart arrhythmia. If left untreated, pernicious anemia can cause nerve damage. Nerve damage can result in a tingling and numbness sensation in the hands and feet, loss of normal reflexes, muscle weakness, difficulty walking and unsteadiness, according to the National Heart, Lung and Blood Institute.
Diagnosis
A doctor will use a blood test called a complete blood count, or CBC, to diagnosis pernicious anemia. A CBC measures the levels of red blood cells contained in the blood, or hematocrit, as well as the amount of hemoglobin in the blood. Normal hematocrit values range between 32 percent and 43 percent; normal hemoglobin ranges between 11 g/dL and 15 g/dL of blood, according to MayoClinic.com.
Treatment
Treatment for pernicious anemia focuses on restoring vitamin B12 levels. In mild cases, this can be achieved through the use of oral supplements of vitamin B12. Those with severe deficiencies, or deficiencies caused by absorption problems, may require regular, monthly injections of vitamin B12.
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