Pernicious anemia is an autoimmune disorder in which the body doesn’t produce enough healthy red blood cells due to its inability to absorb vitamin B12.
“Pernicious” actually means “deadly” and is used because it was once considered a deadly disease due to the lack of available treatment. However, failure to diagnose and treat in time can result in severe neurologic complications, leading to death.
The disease was first clearly described in 1849 by Thomas Addison, from which it acquired the common name of Addison’s anemia. It may also be referred to as Vitamin B12 deficiency.
Causes of Pernicious Anemia
Intrinsic Factor and Vitamin B12 Absorption
Pernicious anemia is caused by a lack of intrinsic factor (IF) in the stomach, which causes B12 deficiency. Intrinsic factor is a protein produced by the parietal cells of the gastric mucosa (stomach lining) that is necessary for the absorption of vitamin B12 later on in the small intestine.
Vitamin B12 is not produced by the body and must be obtained from the diet. B12 is naturally found in animal products including meat, poultry, fish, eggs, and dairy products. Fortified cereals and nutritional supplements are another source.
When vitamin B12 is consumed, it travels to the stomach where it binds with intrinsic factor (IF), and the two are then absorbed in the last part of the small intestine.
In most cases of pernicious anemia, the body’s immune system attacks and destroys the cells that produce IF in the stomach. When these cells are destroyed, the body can’t make IF and therefore can’t absorb vitamin B12.
Sometimes other causes of vitamin B12 deficiency, such as poor diet, are confused with pernicious anemia. However, pernicious anemia is strictly caused by a lack of IF, whether that be due to an autoimmune disorder, gastrectomy or gastric bypass surgery, or a genetic defect in which a child is born not making IF.
Vitamin B12 Deficiency and Red Blood Cells
Without enough B12, the body will produce macrocytes (abnormally large red blood cells) which may not be able to enter the bloodstream from the bone marrow, resulting in a decrease in oxygen-carrying RBCs in the bloodstream.
Pernicious anemia is sometimes called megaloblastic anemia because of the abnormally large size of RBCs produced.
It is not preventable and occurs in about 1 in 1,000 people, usually between the ages of 40 and 70. Patients with pernicious anemia often have other autoimmune disorders as well as a 2–3 times increased risk of gastric cancer.
Symptoms of Pernicious Anemia
Classic Symptoms
The signs and symptoms of pernicious anemia are usually subtle and vague, and many are due to anemia itself.
There is a triad of classic symptoms including:
- Weakness/fatigue
- Sore tongue (glossitis)
- Skin tingling (paresthesia)
However, these are not always seen in all patients.
Common Signs and Symptoms
There are many other common symptoms, including:
- Slight jaundice
- Pale skin with dark circles around the eyes
- Thinning and early graying of the hair and brittle nails
- Headaches
- Low-grade fever
- Depressive mood
- A swollen, red, smooth tongue
- Sores at the corner of the mouth (angular cheilitis)
- Loss of appetite/weight loss
- Pica (desire to eat non-food items, such as ice, dirt, or paper)
- Tachycardia/chest pain/evidence of CHF
- Altered blood pressure
- Shortness of breath
- Nerve damage (can be permanent if treatment not started within 6 months of symptoms)
Neurological Symptoms
Severe pernicious anemia can lead to neurological symptoms, including:
- An unsteady gait, clumsiness
- Stiffness and tightness in the muscles
- Numbness in arms and legs
- Dementia, psychotic depression, psychosis
- Progressive lesions of the spinal cord
- Death in serious cases
Diagnosis and Treatment
Diagnostic Tests
Diagnosis of pernicious anemia involves several tests:
- CBC (complete blood count)
- Blood smear
- Vitamin B12 deficiency blood test
- Intrinsic factor (IF) antibody blood test
- Evaluation of gastric secretions
- Stomach biopsy to look for cell damage
- Schilling test, however it is no longer widely used
Vitamin B12 Therapy
Treatment for pernicious anemia involves administration of vitamin B12 (either cyanocobalamin or hydroxocobalamin), which will stop anemia-related symptoms and neurological deterioration. If neurological problems are not advanced, complete remission of all symptoms will occur as long as B12 is supplemented.
Standard treatment of B12 is usually by intramuscular (IM) injection, but oral doses also appear to be effective. Other methods include sublingual and intranasal treatment, and experimental transdermal patches.
Long-Term Follow-Up
Patient follow-up is required to make sure they respond to therapy and that they continue to receive therapy for the rest of their lives.
B12 therapy resolves the anemia, however, it does not cure the chronic inflammation of the stomach mucosa, which can progress to gastric cancer.
Nursing Care and Patient Education
When caring for the patient with pernicious anemia, the nurse should:
- Remind patients that their family members are at a greater risk of developing the disease and should be monitored for anemia and mental or neurological symptoms.
- Teach the patient about eating a diet rich in vitamin B12.
- Instruct strict vegetarians, particularly those who do not eat eggs, milk, or meat to take supplementary B12 for their lifetime, especially during pregnancy and breastfeeding.
Review
- The body requires vitamin B12 and the protein called intrinsic factor (IF) to make red blood cells.
- Pernicious anemia is an autoimmune disorder in which the body doesn’t produce enough healthy red blood cells due to its lack of IF and inability to absorb vitamin B12.
- The three symptoms seen most often include weakness/fatigue, sore tongue, and skin tingling. If not treated, symptoms can become more severe, leading to death.
- Treatment involves lifelong administration of B12, but a person that is well-treated can live a healthy life.
