Pernicious anemia is a disease in which large, immature, nucleated cells (megaloblasts, the precursors of red blood cells) circulate in the blood and do not function as blood cells; It is a disease caused by the deterioration of vitamin B12 intake due to the lack of intrinsic factor in the gastric mucosa.
What is pernicious anemia?
Pernicious anemia is a rare blood disorder characterized by the body’s inability to properly use vitamin B12, which is essential for the development of red blood cells. Most cases are caused by a deficiency of the gastric protein known as intrinsic factor, from which vitamin B12 cannot be absorbed.
Symptoms of pernicious anemia may include weakness, fatigue, stomach upset, an abnormally fast heartbeat (tachycardia), or chest pains. Recurrent episodes of anemia (megaloblastic) and abnormal yellow coloring of the skin (jaundice) are also common. Pernicious anemia is thought to be an autoimmune disease , and some people may have a genetic predisposition to this disease.
There is a rare form of congenital pernicious anemia in which babies are born lacking the ability to produce effective intrinsic factor. There is also a juvenile form of the disease, but pernicious anemia usually does not appear before the age of 30. The onset of the disease is slow and can last for decades. The disease may go unnoticed for a long time and may lead to neurological complications if left untreated. Because nerve and blood cells need vitamin B12 to function properly.
What causes pernicious anemia?
Pernicious anemia is a type of vitamin B12 anemia. The body needs vitamin B12 to make red blood cells. You get this vitamin from foods such as meat, poultry, shellfish, eggs, and dairy products.
A special protein called intrinsic factor makes vitamin B12 absorbable in the intestines so it can be absorbed in the intestines. This protein is released by cells in the stomach. If the stomach does not make enough intrinsic factor, the gut cannot absorb vitamin B12 properly.
Common causes of pernicious anemia include:
- Weakened stomach lining (atrophic gastritis)
- An autoimmune condition in which the body’s immune system attacks the intrinsic factor protein, or cells in the lining of the stomach
In rare cases, this type of anemia is passed down genetically in families. This is called congenital pernicious anemia. Babies with this type of anemia do not make enough intrinsic factor or cannot properly absorb vitamin B12 in the small intestine.
In adults, symptoms of this type of anemia usually do not appear before the age of 30. The average age at diagnosis is 60.
You are more likely to develop this disease if:
- be of Scandinavian or Northern European descent
- Having the same disease in the family history
Certain diseases may also increase your risk, such as:
- Addison’s disease
- Graves’ disease
- Myasthenia Gravis
- Loss of normal function of the ovaries before age 40 (primary ovarian failure)
- type 1 diabetes
- testicular dysfunction
- vitiligo disease
- Sjogren’s syndrome
- Hashimoto’s disease
- celiac disease
Pernicious anemia may also occur after gastric bypass surgery.
What are the symptoms of pernicious anemia?
Symptoms of pernicious anemia include fatigue, shortness of breath, rapid heart rate, jaundice or paleness, tingling and numbness in the hands and feet, loss of appetite, diarrhea, feeling of loss of balance when walking, bleeding gums, impaired sense of smell, and confusion.
Symptoms of the form called juvenile pernicious anemia are usually evident between the ages of 4 and 28 months. Most affected infants develop an anemia known as megaloblastic anemia. The blood (megaloblasts) contain large, immature red blood cells, which impair the blood’s ability to deliver oxygen to the body’s tissues. Other types of blood cells (eg, platelets and white blood cells) may also be deficient (pancytopenia). Symptoms may include vomiting, diarrhea, fatigue, headache, insomnia, loss of appetite, failure to thrive, jaundice, irritability, and pale skin. Mental retardation is also common in infants with juvenile pernicious anemia. Affected infants may experience recurrent episodes of extreme anemia and jaundice.
Individuals with congenital pernicious anemia have symptoms very similar to the juvenile form. However, they progress relatively slowly; happens so slowly that signs of neurological deficits may precede those associated with a decrease in blood capacity. Symptoms may include general weakness, shortness of breath, abnormally fast heartbeat (tachycardia), or chest pains. Affected individuals may also have gastrointestinal problems such as loss of appetite (anorexia), abdominal pain , indigestion, belching or constipation and diarrhea. Weight loss is also common. Some people with pernicious anemia may have an abnormally enlarged liver (hepatomegaly) or spleen (splenomegaly). Other problems involving urinary function may also develop.
Because nerve cells need vitamin B12 to function properly, some people affected by this type of anemia experience neurological symptoms. Nerves other than the brain and spinal cord (peripheral nervous system) are often affected. Sometimes this can involve the spinal cord. Neurological symptoms may include numbness, tingling, loss of feeling in the arms or legs (acroparesthesias). Other neurological symptoms may include decreased ability to coordinate movement or exaggerated reflexes (hyperreflexes). Some people with pernicious anemia may become extremely irritable or depressed, and in some rare cases may even experience paranoia (megaloblastic insanity).
How is pernicious anemia diagnosed?
The first step is always a thorough health history screening and physical examination by a doctor. The results of this examination are used to help direct further testing. A number of laboratory tests are available that can help diagnose pernicious anemia and other causes of vitamin B12 deficiency.
These tests include:
- complete blood cell count
- Examination of the blood smear (peripheral smear) under the microscope, usually done in conjunction with a complete blood cell count
- Measurements of vitamin B12 level in the blood
- Tests for the presence of autoantibodies such as intrinsic factor
- Iron levels in the blood and its capacity to bind iron
- Folate levels (usually reduced when vitamin B12 levels are low)
- Blood levels of methylmalonic acid or homocysteine, both of which can be sensitive indicators of vitamin B12 deficiency
- The Schilling test, a measure of how well the body can absorb vitamin B12, is less used today than in the past.
- Finally, bone marrow aspiration or bone marrow biopsy may be recommended in some cases if bone marrow disorders are suspected.
How is pernicious anemia treated?
The symptoms of pernicious anemia and vitamin B12 deficiency can be treated by replenishing the supply of vitamin B12 in the body. If a condition other than pernicious anemia is responsible for vitamin B12 deficiency, treatment should be directed at the underlying condition. Symptoms of vitamin B12 deficiency may improve after just a few days of medical treatment.
Vitamin B12 is typically given as an intramuscular injection. A 1000 microgram (1mg) injection of vitamin B12 is usually given daily for one week, followed by 1mg per week for four weeks and then 1mg every month thereafter.
Alternative treatments for this type of anemia include high-dose oral vitamin B12 because the gut has a less efficient absorption system for vitamin B12 that does not require the presence of intrinsic factor. However, the oral dose required for this type of therapy (1 to 2 milligrams/day) is 200 times greater than the minimum daily requirement of vitamin B12 for healthy adults. Nasal spray and sublingual vitamin B12 preparations are also available and under investigation.
Remember, your doctor will decide which medicine to take and how.
Can pernicious anemia be prevented?
The autoimmune process that causes pernicious anemia cannot be prevented. Vitamin B12 deficiency caused by conditions such as other gastrointestinal diseases and gastrointestinal surgery is preventable only to the extent that these causative conditions are preventable themselves.
Vitamin B12 is obtained from animal sources (for example, meat, fish, poultry, dairy), but vitamin B12 deficiency in vegetarians or vegans can be prevented by using oral vitamin B12 supplements. Pregnant and breastfeeding women who are vegetarian or vegan are often low in B12 levels and should consult their doctor.