Pernicious Anemia or Addison–Biermer Anemia: Causes, Risk Factors, Symptoms, Treatment
Pernicious anemia is a type of anemia where the body is not able to produce enough healthy RBCs or red blood cells due to deficiency of Vitamin B12.
Vitamin B12 is found in some foods and this nutrient is important for the body to produce healthy red blood cells and also for proper functioning of the nervous system. Individuals suffering from pernicious anemia are not able to absorb the required amount of vitamin B12 from food, as they don't have intrinsic factor, which is a protein produced in the stomach. Absence of this protein causes vitamin B12 deficiency, which results in pernicious anemia.
Other Factors Causing Vitamin B12 Deficiency Are: Surgery, infections, poor diet and certain medicines.
Due to lack of vitamin B12, there is abnormal division of the red blood cells resulting in them being too large in size, which makes it difficult for them to get out of the bone marrow. The main function of red blood cells is carrying oxygen all over the body, and due to deficiency of the red blood cells, the body does not receive enough oxygen and this results in tiredness and weakness. Severe or persistent pernicious anemia can be very dangerous, as it can cause damage to the brain, heart and other important organs of the body. Other problems occurring due to pernicious anemia are: Damage to the nerves, neurological problems like memory loss, and problems with the digestive tract. Pernicious anemia also puts a person at a higher risk for stomach cancer and decreased bone strength.
In the past, pernicious anemia was considered to be fatal, as proper treatment was not there; however, in today's time, pernicious anemia can be easily treated by giving vitamin B12 orally or via injections.
Pernicious anemia is considered to be an autoimmune disorder when the vitamin B-12 doesn't get absorbed from the gastrointestinal tract due to presence of autoantibodies produced by our own body against the intrinsic factor (IF), which is a protein required for proper absorption of vitamin B-12.
Congenital pernicious anemia is a condition occurring in individuals who are born with a disorder, which prevents their bodies from producing the intrinsic factor.
Causes of Pernicious Anemia or Addison–Biermer Anemia
The main cause of pernicious anemia is malabsorption of vitamin B12, which in turn occurs from lack of the intrinsic factor. If this intrinsic factor is not made due to antibodies produced by our own body against this IF or protein (autoimmune response), then pernicious anemia is considered to be an autoimmune disorder. The cause for this is not clear.
Deficiency of vitamin B12 leading to pernicious anemia can be due to other causes also, such as infections, medicines, surgery or diet lacking in vitamin B12.
Causes of Malabsorption of Vitamin B12 in the Small Intestine
- If the small intestine harbors the wrong type of bacteria then these bacteria absorb all the vitamin B12 and our small intestine does not get the chance to absorb it, thus leading to pernicious anemia.
- Certain medical conditions hinder with the vitamin B12 absorption such as celiac disease, Crohn's disease and HIV.
- There are some medicines, such as antibiotics, seizure and diabetes medicines, which change the growth of the bacteria or impede the small intestine from complete or proper absorption of vitamin B12.
- Surgery requiring removal of a segment or the entire small intestine also results in malabsorption of vitamin B12 and thus pernicious anemia.
- Having an infection, such as tapeworm infection, also results in malabsorption of vitamin B12, as the tapeworm uses the vitamin B12.
- People who consume diet which lacks in vitamin B12 also suffer from pernicious anemia. Foods containing vitamin B12 are: Breakfast cereals with fortified with B12, meats (beef, fish,poultry), dairy products, eggs, soy-based beverages, which are fortified with vitamin B12.
Risk Factors for Pernicious Anemia or Addison–Biermer Anemia
- Vegetarians are at a risk for pernicious anemia.
- Breastfed babies of vegetarian mothers are also at risk for pernicious anemia.
- People from African and Northern European descent are at a higher risk for pernicious anemia.
- Having a family history of pernicious anemia puts you at a higher risk for developing it.
- Older people are at an increased risk for pernicious anemia.
- People who have had their intestine surgically removed are at a risk for pernicious anemia.
- Having other autoimmune diseases, such as Graves' disease, Addison's disease, type 1 diabetes etc. puts you at an increased risk for pernicious anemia.
- Having certain diseases, such as intestinal infections, Crohn's disease and HIV increases your risk for developing pernicious anemia.
Signs and Symptoms of Pernicious Anemia or Addison–Biermer Anemia
- Chest pain.
- Shortness of breath.
- Weight loss.
- Coldness felt in the hands and feet.
- Constipation or diarrhea.
- Abdominal bloating.
Severe Symptoms of Pernicious Anemia or Addison–Biermer Anemia Include
- Gait disturbances and balance problems.
- Progressive spinal cord lesions.
- Muscle tightness or stiffness (spasticity).
- Muscle weakness.
- Nerve damage in the arms and legs (peripheral neuropathy).
- Memory loss.
- Loss of reflexes.
- Heart problems (heart murmur/heart enlargement/heart failure).
- Enlarged liver.
- Weakened bones.
Investigations for Pernicious Anemia or Addison–Biermer Anemia
- Medical and family history.
- Physical exam where the doctor will check for skin pallor, liver enlargement, rapid/irregular heartbeats, heart murmur and signs of nerve damage along with assessing patient's mental condition, balance and coordination.
- Bone marrow biopsy or bone marrow aspiration to look for any bone marrow disorders.
Blood Tests such as:
- Complete blood cell count (CBC).
- Peripheral smear examination.
- Measuring the level of vitamin B12 in the blood.
- To check for the autoantibodies against the intrinsic factor.
- Level of iron-binding capacity in the blood.
- Folic acid levels.
- Measuring the level of methylmalonic acid and homocysteine.
- Schilling test to assess the body's ability to absorb vitamin B12.
Treatment for Pernicious Anemia or Addison–Biermer Anemia
- Treatment comprises of replacing the deficient vitamin B12 in the body after, which the patient can feel an improvement in the symptoms within a few days. If the pernicious anemia and vitamin B12 deficiency is due to other causes, then that underlying medical condition is treated.
- Vitamin B12 injections are commonly given intramuscularly.
- Vitamin B12 can also be given orally in high dosages for pernicious anemia.
- Vitamin B12 in the form of nasal spray and sublingually are an option; however, they are still under study.
- It is advisable to restrict physical activity till the symptoms subside.
Pernicious Anemia or Addison–Biermer Anemia Often Requires Lifelong Treatment And The Aim Of Treatment Includes:
- Preventing or alleviating the signs and symptoms of pernicious anemia.
- Preventing or managing its complications, such as damage to the nerves and heart.
- Treating the main underlying cause.
Prevention of Pernicious Anemia or Addison–Biermer Anemia
- If pernicious anemia occurs as a result of autoimmune dysfunction, then it cannot be prevented.
- For other causes patients should try to improve their diet by eating foods, which contain vitamin B12, such as beef, poultry, liver, fish, eggs, yogurt, milk, yogurt and cheese.
- Vegetarians (and also non-vegetarians) can increase their intake of breakfast cereals which have added vitamin B12 and soy-based beverages which are fortified with vitamin B12.
- Older people and individuals with stomach surgery should take B-complex vitamin supplements.
Prognosis of Pernicious Anemia or Addison–Biermer Anemia
Pernicious anemia, if left untreated, can be fatal and result in death. Patients can suffer from neurological, cardiovascular, gastrointestinal problems/complications etc. Treatment is often needed and continued for the patient's whole life. People suffering from pernicious anemia are also at an increased risk for stomach cancer.