Anemia Due to Vitamin B12 Deficiency

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Anemia Due to Vitamin B12 Deficiency


Anemia Due to Vitamin B12 deficiency (pernicious anemia) is the megaloblastic anemia caused by vitamin B12 deficiency. In addition to iron, bone marrow requires vitamin B12 and folic acid to produce red blood cells. If one of these deficiencies, megaloblastic anemia may occur.

On this type of anemia, the bone marrow produces red blood cells and abnormal large (megaloblas). White blood cells and platelets are also usually abnormal.

Megaloblastic anemia is most often caused by a deficiency of vitamin B12 and folic acid in foods or the inability to absorb vitamin. Sometimes anemia is caused by certain drugs used to treat cancer (eg, methotrexate, hydroxyurea, fluorouracil and cytarabine).


Inadequate absorption of vitamin B12 (cobalamin) causes pernicious anemia. Vitamin B12 is widely available in the flesh and in normal circumstances have been absorbed at the end of the small intestine leading to the large intestine (ileum).

In order to be absorbed, vitamin B12 must be joined with intrinsic factor (a protein made in the stomach), which then carries these vitamins to the ilium, through the walls and into the bloodstream. Without intrinsic factor, vitamin B12 remains in the intestine and excreted through the feces.

On pernicious anemia, gastric intrinsic factor can not form, so that vitamin B12 can be absorbed and there was no anemia, although a large amount of vitamins consumed in the daily diet. But because the liver stores of vitamin B12 sejumla, the anemia will not usually appear until about 2-4 years after the body stops absorbing vitamin B12.

In addition to its lack of intrinsic factors, other causes of vitamin B12 deficiency are:

– The growth of abnormal bacteria in the small intestine that prevents absorption of vitamin B12

– A specific disease (eg Crohn disease)

– Removal of the stomach or part of the small intestine where vitamin B12 is absorbed

– Vegetarian.


In addition to lessen the formation of red blood cells, deficiency of vitamin B12 also affects the nervous system and cause:

– Tingling in hands and feet

– Loss of feeling in legs, feet and hands

– Rigid movement.

Other symptoms are:

– A certain color blindness, including yellow and blue

– Open sores on the tongue or tongue burning

– Weight loss

– Skin color becomes darker

– Dazed

– Depression

– Decline in intellectual function.


Normally, vitamin B12 deficiency was diagnosed on routine blood tests for anemia. In the blood sample is examined under a microscope, looks megaloblas (large red blood cells). You can view changes in white blood cells and platelets, especially if the patient had suffered from anemia in the long term.

If a deficiency is suspected, then measured levels of vitamin B12 in the blood. If it is definitely a shortage of vitamin B12, can be examined to determine the cause.

Usually the inspection focused on the intrinsic factors:

Blood samples were taken to check the presence of antibodies to intrinsic factor.

These antibodies are usually found in 60-90% of patients with pernicious anemia.

A more specific, the analysis of the stomach.

Inserted a small tube (nasogastric tube) through the nose, throat and pass into the stomach.

Then injected pentagastrin (merangasang hormone release intrinsic factor) into a vein.

Further gastric fluid samples taken and examined for presence of intrinsic factor.

If the cause is still uncertain, Schilling test can be done. Given a small amount of radioactive vitamin B12 by mouth (swallowed) and the measured absorption. Then, given the intrinsic factor and vitamin B12, and absorption was measured again. If vitamin B12 is absorbed by intrinsic factor, but not be absorbed without intrinsic factor, then the diagnosis is definite pernicious anemia.


Treatment of vitamin B 12 deficiency or pernicious anemia are vitamin B12. Most people can not absorb vitamin B12 by mouth (swallowed), because it is given by injection.

At first the injections are given every day or every week, for several weeks until the levels of vitamin B12 in the blood return to normal. The next shot is given 1 time / month.

Patients should consume extra vitamin B12 throughout his life.


If the cause is a lack of intake, the anemia can be prevented through a balanced diet.


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