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Published by Bupa's health information team, February 2008.
This factsheet is for people who have pernicious anaemia, or who would like information about it.
Anaemia is a condition where you have too few red blood cells or not enough haemoglobin in your blood. It can make you feel tired, breathless and faint. Pernicious anaemia is where your body doesn't absorb enough vitamin B12 from your diet because of a lack of a substance that is needed to help with this process.
About pernicious anaemia
Pernicious anaemia is an autoimmune disease. Usually your immune system, which helps your body fight infection, produces white cells and proteins called antibodies to destroy foreign substances such as viruses and bacteria. With autoimmune diseases, your immune system mistakes your own tissue as foreign and attacks it, leading to inflammation. In pernicious anaemia, the inflammation occurs in the lining of your stomach.
In healthy people, certain cells in the stomach called parietal cells produce a substance called intrinsic factor. Your body needs this in order to absorb vitamin B12 from the lower part of your small bowel. You need vitamin B12 to make new cells, including red blood cells which carry oxygen.
You can only get vitamin B12 through your diet because your body can't produce or store it. If you have pernicious anaemia, your immune system produces antibodies which attack either the parietal cells or intrinsic factor itself. Therefore, even if you are eating enough vitamin B12, you can't absorb it.
Usually, the parietal cells also produce acid to help digest food in the stomach. If you have pernicious anaemia, these cells won't produce as much acid and maybe even none at all.
Vitamin B12 is important for the production of DNA - this is the material that determines how each cell of your body looks and behaves. If you don't have enough vitamin B12, your body won't be able to make DNA properly and so cells may develop abnormally. This includes cells produced in your bone marrow, the soft tissue found inside your bones such as red blood cells which carry oxygen around your body. The cells of the nervous and digestive systems may also be affected.
Pernicious anaemia can produce a wide range of symptoms including:
feeling out of breath on exertion
loss of appetite
tingling, itching or "pins and needles" sensations on your skin
lack of concentration
mild jaundice (yellowing of your skin and the whites of your eyes)
If your pernicious anaemia is more advanced, you may also have psychiatric problems such as depression or dementia. In severe cases you may also develop problems with your heart.
Although not necessarily a result of pernicious anaemia, if you have these symptoms you should visit your GP.
The reasons why your immune system causes an autoimmune reaction resulting in pernicious anaemia are not fully understood at present. However, there are certain things that seem to make some people more likely to develop the condition.
Your risk increases with age - about one in 1,000 people over the age of 60 develop pernicious anaemia. Only one in 10,000 people under the age of 40 develop pernicious anaemia.
You are slightly more at risk if you are a woman.
In three out of every 10 people who have pernicious anaemia, someone else in their family also has the condition.
If you have another autoimmune disease such as a thyroid problem or Addison's disease, you may be at a greater risk of developing pernicious anaemia.
You may be more likely to develop pernicious anaemia if your blood type is group A.
Your GP will ask about your symptoms and examine you. He or she may also ask you about your medical history. In many people, pernicious anaemia can be diagnosed by blood tests which will check for:
a low level of red blood cells
enlarged red blood cells
antibodies which are attacking either your parietal cells or intrinsic factor
the level of vitamin B12 in your blood
It's possible that you will be referred to a haematologist, a doctor specialising in identifying and treating conditions of the blood. He or she may take a sample of your bone marrow to be examined.
Nine out of 10 people with pernicious anaemia have antibodies to parietal cells. However, some people who don't have pernicious anaemia do have antibodies to parietal cells so this won't always give a reliable diagnosis of the condition.
If tests show that you have antibodies to intrinsic factor, it's very likely that you have pernicious anaemia. However, they are found in only half of all people with the condition.
If a diagnosis can't be made, you may be asked to take another test called a Schilling test to see if your body is able to absorb vitamin B12. This helps to determine whether or not your vitamin B12 deficiency is due to pernicious anaemia.
The test involves taking a drink containing a small amount of radioactive vitamin B12 and then collecting your urine for the next 24 hours. This can then be tested to see if it contains vitamin B12 - if it does, this means it has been absorbed in your small bowel.
A few people may need to have further tests such as a gastroscopy to check whether something other than pernicious anaemia is causing the vitamin B12 deficiency. A gastroscopy is a test that allows your doctor to look inside your stomach using a narrow, flexible, tube-like telescope called an endoscope.
It's important to start treatment for pernicious anaemia as early as possible, especially if you have symptoms of nerve damage. If treatment is delayed, it may mean that it isn't possible to reverse any effects this has had.
If you have pernicious anaemia, you will need to have regular injections of vitamin B12. You are most likely to receive vitamin B12 in the form of a substance called hydroxocobalamin. You need to receive it by injection into a muscle because if you take it by mouth, your body won't absorb it.
Soon after you have been diagnosed with pernicious anaemia, you will receive what is known as a loading dose of vitamin B12. This is to build up your levels of vitamin B12 quickly and will probably involve injections every day or every other day for two weeks. You will then need to have regular injections at intervals of between one and three months.
It's possible that you will need to have regular blood tests to check your levels of red blood cells and vitamin B12.
Living with pernicious anaemia
It's likely that your condition will improve quickly once you start having injections and you should be able to live your life as before. However, you will need to carry on having vitamin B12 injections indefinitely.
Pernicious anaemia Q&As
See our answers to common questions about pernicious anaemia, including:
- Anaemia - macrocytic. NHS Library for Health. Clinical Knowledge Summaries. http://cks.library.nhs.uk, accessed 23 August 2007
- Longmore M, Wilkinson IB, Rajagopalan S. Oxford Handbook of Clinical Medicine. Oxford: Oxford University Press, 2004:634
- Vitamin B12. The Vegetarian Society. www.vegsoc.org, accessed 23 August 2007
- Vitamin B12. Food Standards Agency. www.eatwell.gov.uk, accessed 23 August 2007
- Pernicious Anaemia. Pernicious Anaemia Society. www.pernicious-anaemia-society.org, accessed 23 August 2007
- British National Formulary (BNF). Drugs used in megaloblastic anaemias. BMJ Publishing Group, 2007. 53:483
This information was published by Bupa's health information team and is based on reputable sources of medical evidence. It has been peer reviewed by Dr John Houghton FRCP FRCPath, Consultant Haematologist, Salford Royal Hospital Trust, and by Bupa doctors. It has been patient reviewed by the Pernicious Anaemia Society. The content is intended for general information only and does not replace the need for personal advice from a qualified health professional.
Publication date: February 2008.