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Pernicious anemia (PA) is an autoimmune disorder that causes psychiatric, neurological changes, including dementia, deafness and a condition of anemia related to vitamin B12 deficiency.
Vitamin B12 is a nutrient derived from dietary such as beef, poultry, fish, cheese, eggs and cereals. Vitamin B12 is absorbed in the stomach . Pernicious anemia (PA) is an autoimmune condition of anemia caused by a deficiency of vitamin B12. Vitamin B12 deficiency can have many causes including PA, malabsorption syndromes, and food cobalmin deficiency. In PA, an autoimmune process that inactivates intrinsic factor or damages parietal cells or their proton pumps leads to the disease process. Vitamin B12 deficiency in PA occurs when autoantibodies to intrinsic factor or parietal cells reduce levels of intrinsic factor by interfering with its absorption.
B12 deficiency can lead to many symptoms.
Your body needs vitamins — nutrients found in most foods — for many reasons, including producing healthy red blood cells. If your body is deficient in certain key vitamins, you can develop anemia — a condition in which your blood is low on healthy red blood cells.
Red blood cells carry oxygen from your lungs to all parts of your body. Without enough healthy red blood cells, your body can't get the oxygen it needs to feel energized. To produce red blood cells, your body needs iron and certain vitamins.
Vitamin deficiencies also can lead to health problems other than anemia. Fortunately, you can usually correct vitamin deficiencies with supplements and dietary changes.
Signs and symptoms
Anemia occurs in many types, but the main symptom of most anemias is fatigue. That's true for vitamin deficiency anemias, which can also result in:
Sore mouth and tongue
Shortness of breath
Loss of appetite
Numbness or tingling in your hands and feet
In addition, vitamin B-12 deficiency can also result in:
Loss of balance
Mental confusion or forgetfulness
Vitamin deficiencies usually develop slowly, over several months to years. Signs and symptoms may be subtle at first, but they increase as the deficiency worsens.
Blood consists of liquid called plasma and three types of blood cells:
White blood cells. These blood cells fight infection.
Platelets. These blood cells help your blood clot.
Red blood cells (erythrocytes). These blood cells carry oxygen from your lungs, by way of your bloodstream, to your brain and the other organs and tissues. Your body needs a supply of oxygenated blood to function. Oxygenated blood helps give your body its energy and your skin a healthy glow.
All three types of blood cells are produced regularly in your bone marrow — a red, spongy material located within the cavities of many of your large bones. To produce adequate numbers of healthy blood cells, especially red blood cells, your bone marrow needs a steady supply of iron, vitamin B-12, folate and vitamin C from your diet.
You need iron because red blood cells contain hemoglobin — an iron-rich substance that enables them to carry oxygen. Vitamin B-12 and folate are necessary because they're building blocks of red blood cells. Vitamin C aids in the formation of red blood cells by helping you absorb iron.
A shortage of healthy red cells
With a shortage of iron, your bone marrow produces fewer and smaller red blood cells. Anemia caused by a lack of vitamin C causes the bone marrow to make smaller red blood cells. Without enough vitamin B-12 or folate, your bone marrow produces large and underdeveloped red blood cells called megalocytes. The result is a shortage of healthy red blood cells — anemia.
Anemia caused by a lack of iron is called iron deficiency anemia. Causes of vitamin deficiency anemias, also known as megaloblastic anemias, include:
Folate deficiency anemia. Folate, also known as vitamin B-9, is a nutrient found mainly in citrus fruits and leafy green vegetables. A diet consistently lacking in these foods can lead to a deficiency. An inability to absorb folate from food also can lead to a deficiency. Most nutrients from food are absorbed in your small intestine. People with diseases of the small intestine, such as Crohn's disease or celiac disease, or those who have had a large part of their small intestine surgically removed or bypassed may have difficulty absorbing folate or its synthetic form, folic acid. Alcohol decreases absorption of folate, so drinking alcohol to excess may lead to a deficiency. Certain prescription drugs, such as some anti-seizure medications, can interfere with absorption of this nutrient. Pregnant women and women who are breast-feeding have an increased demand for folate, as do people undergoing hemodialysis for kidney disease. Failure to meet this increased demand can result in a deficiency. Your body stores some folate, but anemia can develop within months if your body's reserves are depleted.
Vitamin B-12 deficiency anemia (pernicious anemia). Rarely, vitamin B-12 deficiency results from a diet lacking in vitamin B-12, which is found mainly in meat, eggs and milk. Most often, a shortage occurs because your small intestine can't absorb vitamin B-12. This may be due to surgery to your stomach or small intestine, such as gastric bypass surgery, abnormal bacterial growth in your small intestine, or an intestinal disease, such as Crohn's disease or celiac disease, that interferes with the absorption of the vitamin. Vitamin B-12 deficiency can also be caused by a tapeworm ingested from contaminated fish, because the tapeworm saps nutrients from your body. However, a deficiency is most often due to a lack of a substance called intrinsic factor. Vitamin B-12 is broken down from food in your stomach. Intrinsic factor is a protein secreted by the stomach that joins with vitamin B-12 in the stomach and then escorts it through the small intestine to be absorbed into your bloodstream. Without intrinsic factor, vitamin B-12 can't be absorbed and leaves the body as waste. Lack of intrinsic factor may be due to an autoimmune reaction, in which your immune system mistakenly attacks the stomach cells that produce intrinsic factor. Or it may be due to a genetic defect that suddenly halts production of the protein in your adult years. Vitamin B-12 deficiency ultimately leads to anemia. If the deficiency is from a lack of intrinsic factor, it's called pernicious anemia. Pernicious means deadly. Lack of intrinsic factor was often fatal before the availability of vitamin B-12 shots. Because vitamin B-12 is stored in large amounts in your liver, it may take several years before you develop signs of a deficiency.
Vitamin C deficiency anemia. A lack of vitamin C in your diet can cause this type of anemia. Your body needs vitamin C, found mainly in citrus fruits, to produce healthy blood cells. Vitamin C also helps your body absorb iron, an important building block of red blood cells.