In pernicious anemia, your body cannot absorb enough vitamin B12 from your diet. Deficiencies in vitamin B12 are associated with fatigue, weakness, pale skin, shortness of breath, neurological problems, and a lack of energy. Vitamin B12 is essential for red blood cells, which carry oxygen throughout your body.
Most people with pernicious anemia suffer from an autoimmune condition that affects the stomach. Vitamin B12 is normally absorbed in the small intestine by a substance called intrinsic factor produced by the stomach. In some people, the immune system attacks and destroys intrinsic factor-producing cells, leading to vitamin B12 deficiency.
Other causes of pernicious anemia include:
Surgery or disease that affects the stomach or the small intestine, such as gastric bypass, Crohn’s disease, or celiac disease.
Genetic factors that impair the production or function of intrinsic factor or vitamin B12 transport proteins.
Dietary factors that limit the intake of vitamin B12, such as veganism or vegetarianism.
Some factors that may increase your risk of developing pernicious anemia are:
Family history of the condition.
Age over 60 years.
Northern European or Scandinavian ancestry.
Having other autoimmune diseases, such as type 1 diabetes, thyroid disease, or vitiligo.
To diagnose pernicious anemia, your doctor may perform several tests, such as:
Complete blood count (CBC), which measures the number and size of your red blood cells, as well as the levels of hemoglobin and hematocrit.
Vitamin B12 level, which indicates how much vitamin B12 is in your blood.
Intrinsic factor antibody test, which detects the presence of antibodies against intrinsic factor.
Schilling test, which evaluates how well your body absorbs vitamin B12.
Gastric biopsy, which involves taking a sample of your stomach tissue to check for inflammation or damage.
Bone marrow biopsy, which involves taking a sample of your bone marrow to examine the production of blood cells.
The treatment of pernicious anemia aims to restore and maintain normal levels of vitamin B12 in your body. This can be done by:
Vitamin B12 injections, which are given into a muscle or under the skin, usually once a month or more frequently depending on your needs.
Vitamin B12 pills, which are taken orally, usually once a day or as prescribed by your doctor.
Vitamin B12 nasal spray, which is sprayed into your nose, usually once a week or as prescribed by your doctor.
To correct any other deficiencies or complications, you may also need to take folic acid, iron, or other vitamins and minerals in addition to vitamin B12. As well as consuming vitamin B12-rich foods, such as meat, eggs, dairy products, fish, and fortified cereals, you should follow a balanced diet.
If left untreated, pernicious anemia can lead to serious and irreversible complications, such as:
Nerve damage, which can cause numbness, tingling, pain, or weakness in your hands and feet, as well as problems with balance, coordination, memory, and cognition.
Heart problems, which can cause irregular heartbeat, chest pain, shortness of breath, or heart failure.
Digestive problems, which can cause nausea, vomiting, diarrhea, constipation, or loss of appetite.
Increased risk of infections, due to reduced immunity and increased susceptibility to bacteria and viruses.
Increased risk of certain cancers, especially gastric cancer, due to chronic inflammation and damage to the stomach lining.
To prevent pernicious anemia, you should:
Get regular check-ups and blood tests to monitor your vitamin B12 levels and your overall health.
Follow your doctor’s recommendations for vitamin B12 supplementation and dosage.
Eat a varied and nutritious diet that includes foods rich in vitamin B12, or take fortified foods or supplements if you are vegan or vegetarian.
Avoid alcohol, tobacco, and other substances that may interfere with your vitamin B12 absorption or metabolism.
Seek medical attention if you notice any signs or symptoms of pernicious anemia or vitamin B12 deficiency.