Anaemia due to vitamin B12 deficiency
(Pernicious anaemia)
Summary of review by Dr. Patrick Davey & Dr. Rachel Green
taken from NETDOCTOR.CO.UK
What is anaemia?
Anaemia is a deficiency of red blood cells that can lead to a mild lack of oxygen-carrying ability causing unusual tiredness. Red blood cells are namufactured in the bone marrow and have a life expectancy of approximately four months. Anaemia occurs either through the reduced production of red blood cells or an increased loss of red blood cells.
What are red blood cells?
Red blood cells are the cells that circulate in the blood plasma (fluid). Through its pumping action, the heart propels the blood around the body throught the arteries. The red blood cells obtain oxygen in the lungs and carry it to all the body’s cells.
The cells use the oxygen to fuel the combustion (burning) of sugar and fat which produces the body’s energy.
When the muscles are used. carbon dioxide is created as a waste product. It binds itself to the red blood cells that have delivered their load of oxygen. The carbon dioxide is then transported back to the lungs where it is exchanged for fresh oxygen by breathing.
Why does a vitamin B12 deficiency cause anaemia?
To produce red blood cells, the body needs, among other things iron, vitamin B12, and folic acid (one of the B group vitamins). If one or more of these ingredients is lacking, anaemia will develop.
Vitamin B12 is also essential for the nervous system, which is why a deficiency can also cause inflammation of the nerves, (neuritis) and dementia (mental deterioration).
Vitamin B12 deficiency is frequently caused either by the inability of the small bowel to absorb it, or by a lack of food containing it.
What are the causes of vitamin B12 deficiency?
A vegan diet can cause a deficiency because B12 is only found in foods of animal origin, such as meat, liver, fish, eggs and milk. By far the most common cause of vitamin B12 deficiency is a lack of ‘intrinsic factor’, a substance which is produced in the stomach and enables the body to absorb B12 from the diet.
Causes for a reduced production of intrinsic factor are:
The formation of antibodies against the cells producing intrinsic factor. The cells then die and B12 deficiency and anaemia (also called pernicious anaemia) develop.
Diseases of the small intestine, fish tape worm and the after-effects of surgery to the small intestine can all mean that the surface of the small intestine is too small to obtain B12 and intrinsic factor effectively.
The first symptoms will be unusual tiredness, difficulty in breathing, and dizziness.
What are the symptoms of anaemia due to vitamin B12 deficiency?
Further symptoms specific to vitamin B12 dificiency are:
A red, irritated and possibly shiny, tongue.
A reduced sense of taste.
altered or reduced sense of touch.
Reduced sense of vibration (an inability to feel the vibration of a tuning fork)
Some will experience symptoms in their nervous system first.
Headache
Pains in the legs, & muscle spasm paralysis.
Shortness of breath,
Palpitaion and chest pains,(angina)
Strict vegetarians should take B12 supplements to avoid deficiency. Anyone who has undergone surgery in their small intestine or stomach should pay attention to any of the symptoms mentioned above.
If a blood test shows a low vitamin B12 count, the patient will be given the Schilling test to measure the body’s ability to absorb B12 from the bowel. This will also show whether the anaemia is caused by a lack of intrinsic factor.
B12 injections can be prescribed and will usually be continued throughout the patient’s life.
Prognosis
By eliminating the cause and taking the necessary vitamins by supplement or injection. there will be a complete recovery. However there is a slightly increased risk of permanent damage to the nervous system if the treatment is started too late.
B12 can be destroyed by: Water, sunlight, alcohol, oestrogen, & sleeping pills
Updated July 2003