Anemia is defined as a clinical condition characterized by inadequate oxygen delivery to different body parts due to unhealthy red blood cells. It can be transient or perpetual and symptoms can range from mild, undetectable to severe, inclusive of mortality. Vitamin B12 deficiency over a prolonged period can lead to Pernicious anemia (a type of Megaloblastic anemia), which is characterized by a significant decrease in the number of circulating red blood cells. It happens due to improper or inadequate absorptionof vitamin B12 from the gastrointestinal tract, which is required for red blood cells development. Pernicious anemia builds up over a long period of time before symptoms are visible. Rarely (except for congenital cases), disease onset happens before the age of 30 years and the national average age of diagnosis is 60 years.
Symptoms of pernicious anemia can often mimic anemia caused due to folic acid deficiency (vitamin B9). Hence, vitamin B12 deficiency is sometimes wrongly diagnosed as folate deficiency. Vitamin B12 deficiency results in large, immature, sans-hemoglobin red blood cells that are non-functional. Hence treatment regimen for Megaloblastic anemia should always pre-incorporate diagnostic tests to determine whether it is due to B9 or B12 deficiency.
Causes of Pernicious Anemia: The etiology can vary between malabsorption of the vitamin in the small intestine, which in turn can be caused by a multitude of factors. Important contributory reasons for the aforementioned are abnormal bacterial flora growth in the small intestine, surgical interventions like gastric bypass surgery, and celiac or Crohn’s disease. Rarely tapeworm infestation can also cause pernicious anemia. But perhaps the major reason for pernicious anemia is lack of a protein factor called the Castle’s Intrinsic Factor, which prevents vitamin B12 from degradation before being absorbed by the body. For this reason Vitamin B12 is also called the Castle’s Extrinsic Factor.
Risk Factors for Pernicious Anemia: I cases where many members of the same family are affected it is a hereditary form of the disorder and is usually congenital in its occurrence. Inhibition of Castle’s Intrinsic Factor or complete absence is either due to gastritis (or atrophy) or due to an autoimmune reaction by the body whereby the cells secreting this protein are considered foreign and attacked by body’s own immune system. In such patients oral supplement will not be enough to reverse the deficiency and the only mode of treatment is lifelong intramuscular injection of vitamin B12. Research has shown that North European, especially Scandinavian population, are at a higher risk of vitamin B12 deficiency. Autoimmune disorders, like Graved disease, thyroiditis, Addison’s disease, myasthenia gravis, secondary amenorrhea, type I diabetes, testicular dysfunction and vitiligo also significantly increases the chance of vitamin B12 deficiency.
Treatment: The most common treatment is a subcutaneous or intramuscular injection of vitamin B12. By administering the B12 in this way you bypass the digestive tract and allow the B12 to be absorbed. More recent studies are finding that mega doses of B12 given sublingually works just as well. These are the two most common forms of treatment no matter how you developed vitamin B12 deficiency. As always, discuss your options with your doctor.
Prognosis and Complications: Usually treatment at an early stage gives excellent recovery. Prolonged deficiency can take a toll on neurological controls like limb movements. Treatment must be started within six months to prevent such eventualities. Prolonged period of vitamin B12 deficiency has been reported to cause gastric polyps. Some research has also shown a heightened risk for gastric carcinoid tumors (a very aggressive form of gastric carcinoma).
Preventive Measures: Apparently there is no way to prevent the condition, especially if one has inherited it from their parents. A complete diet with animal proteins or fortified food for vegetarians can go a long way in decreasing the risk of vitamin B12 deficiency. Proper treatment regimen can also help in minimizing complications.