Causes, Symptoms, Treatment and Tests For Pernicious Anemia

Submitted on March 27, 2012

When the blood in a human body is found to have less than the normal number of red blood cells required for healthy living, the condition is described as anemia. Hemoglobin, found in these, is vital for transporting oxygen from the lungs to various parts of the body. Anemia can occur because of loss of blood, reduced red blood cell or hemoglobin production, or an increase in the rate at which red blood cells are destroyed in the body.

Pernicious anemia refers to that kind of anemia where the body is unable to produce enough healthy red blood cells because it is deficient in vitamin B12. Meat, seafood, eggs and poultry, milk and milk products, and whole grains are good sources of vitamin B12. Very often, people with this type of anemia are unable to absorb the vitamin B12 they need in sufficient quantities from the food they consume. This is because their stomach does not produce enough of a particular type of protein known as intrinsic factor, and this protein is essential for the absorption of the B12 vitamin in the person's small intestine. There is a type of pernicious anemia that is congenital, meaning that children are sometimes born with no capacity to produce the intrinsic factor.

This is coupled with the inability to use the vitamin in the small intestine. Apart from the congenital form of this anemia, which appears in infants and children, the disease rarely manifests itself in adults before middle age. The human body stores whatever vitamin B12 is absorbed from the food for a long time, and so the deficiency level does not get severe unless the person consumes a diet lacking in this vitamin for years. Pernicious anemia is also described as a type of megaloblastic anemia because of the abnormally large type red blood cells called megaloblasts produced in the bone marrow of these patients.

Tests Recommended

A pernicious anemia diagnosis is made based on the physical examination, family history, and results from blood tests. Tests for children, adults, or women are required to establish the disease as pernicious anemia before treatment can be started. Here are some of the tests that may be ordered by the doctor:

Complete Blood Count Test

A complete blood count test gives the following information: 
  • White and red blood cell count
  • Hemoglobin content of the blood and amount of hemoglobin in each cell
  • The average size of the red blood cells
  • The platelet count

A reticulocyte test may be performed as a lower than normal number of reticulocytes or immature red blood cells indicates a vitamin B12 deficiency, among others.

Bone Marrow Tests

Bone marrow tests are ordered in case the results for the complete blood count test show abnormal number of red blood cells.

Schilling Test

The Schilling test for vitamin b12 is done in four steps, depending on the outcome of each step.

  • As a first step, after an oral dose and an injection of vitamin B12, the individual's urine is collected over the following 24 hours and examined to see if absorption of the vitamin is normal.
  • If the results of the first step indicate abnormality, the patient is given the vitamin along with the intrinsic factor to rule out problems in the production of the intrinsic factor.
  • Step three is performed after a two-week period of staying off antibiotics to ensure that normal intestinal bacteria are present to absorb the B12vitamin.
  • Performed after ingesting pancreatic enzymes for three days, this fourth step of the test ensures that it is not a problem in the pancreas that inhibits absorption of the vitamin.


One of the main reasons that people get pernicious anemia is the lack of vitamin B12 in their diet over a long period of time. In those cases where it is inherited and there is a lack of intrinsic factor, the children have to inherit one defective gene from each parent in order to get this congenital form of the disease. Vegetarians and vegans who do not eat animal products at all are at risk because they do not get the required amount of cobalamin in their diets. Infants born to vegan mothers need supplements of vitamin B12 as they do not get enough from breast milk. People who have undergone gastric surgery to have a part of their stomach removed, stapled or bypassed as part of the treatment for obesity may develop symptoms of pernicious anemia. This is because, with the reduced size, their stomach may not have enough parietal cells to produce the intrinsic factor in required quantities to absorb vitamin B12 from the limited food consumed. Abnormal bacterial growth in the intestine may also lead to malabsorption in the small intestine leading to cobalamin deficiency.

Another prominent cause of this disease is an unexplained autoimmune disorder in which the body's own immune system produces antibodies to destroy parietal cells in the stomach. These parietal cells line the stomach and produce the intrinsic factor, and destruction of these cells means lower levels of the intrinsic factor, which, in turn,would lead to malabsorption of vitamin B12. Certain diseases like celiac disease or Crohn's disease and HIV may disrupt the absorption of vitamin B12. Similarly, certain medications given to treat seizures, some diabetes medicines, and certain antibiotics may affect the growth of intestinal flora and fauna. This would result in changes in the bacterial composition in the intestine, which may inhibit the absorption of vitamin B12. Long-term use of these medications may result in pernicious anemia.


Since a deficiency of vitamin B12 can affect the nervous system also, it is possible that pernicious anemia symptoms in adults appear as neurological symptoms such as impaired reflexes, feelings of numbness, confusion, lack of co-ordination, dizziness, and so on. Fatigue is a common symptom for all types of anemia since the body lacks enough healthy red blood cells that will provide oxygen to all parts of the body. This also means that the heart has to work harder to ensure that the oxygen rich blood is delivered to all the tissues in the body. Pernicious anemia symptoms in women may include pale skin, brittle nails, and tingling in the hands as also the feet, apart from fatigue and lack of energy. A smooth red tongue that feels thick is also a sign of pernicious anemia in men and women. There is a rare congenital pernicious anemia in autosomal recessive form, which is seen in babies as also children.

Children with this disease are born with the inability to create enough of the intrinsic factor needed for the absorption of vitamin B12 or they lack the capability to absorb the mixture of vitamin B12 and the intrinsic factor in the intestines. Pernicious anemia symptoms in infants include slow reflexes, poor digestion, irritability and facial tremors. Animal products are the most common sources of vitamin B12 or cobalamin. Infants born to mothers who are strict vegans also run the risk of getting pernicious anemia as their bodies have no stores of vitamin B12 to fall back upon. Stunted growth is one of the pernicious anemia symptoms in children. Even a tapeworm infestation in the intestines in children can prevent the absorption of sufficient amounts of vitamin B12. Children with other autoimmune diseases or intestinal disease may be prone to pernicious anemia too, just as children who suffer from the condition due to hereditary causes.


Treatment for pernicious anemia in the initial stages includes dietary measures to consciously include food rich in vitamin B12. In the case of infants of vegan mothers, cobalamin supplements in the form of drops may be administered orally and the mothers may be asked to take vitamin B12 pills so that the breast milk is fortified. In cases where a certain medication is responsible for blocking the absorption of cobalamin, doctors may prescribe an alternative. In more severe cases, an injection of the vitamin is the only pernicious anemia medication that offers quick relief. For patients who lack the intrinsic factor to facilitate the absorption of the vitamin, cobalamin injections work better than oral pills.

Pernicious anemia generally affects the elderly more, and sometimes, older people have a difficulty swallowing pills, particularly after a stroke. For such cases, the vitamin is available in the form of nasal gels and sprays. Since the risk of stomach cancer among people with pernicious anemia is high, it is best to get it treated as early as possible. Prolonged neglect of pernicious anemia can also result in permanent nerve damage and make the neurological symptoms like confusion and dizziness, even worse. Cobalamin therapy involves taking an injection of the vitamin once in three months throughout one's life, particularly for those with impaired absorption due to lack of the intrinsic factor. For severe cases, daily intramuscular injections may be required for a week, and then tapered down to once a week and after four weeks reduced to once a month. Patients with pernicious anemia show marked improvement in symptoms once the therapy is started. Unless the patient's red blood cell count is dangerously low or shows signs of heart failure or circulatory collapse, blood transfusions are not resorted to in cases of pernicious anemia. The emphasis of the treatment is more on replenishing the body's cobalamin stocks with supplements.