What is pernicious anaemia?
Pernicious anaemia is a condition in which the body's immune system attacks stomach cells that produce a protein vital for the absorption of vitamin B12.
Vitamin B12, which is found naturally in meat, fish and dairy products, is absorbed into the body through the stomach. In order for this to happen, gastric parietal cells in the stomach release a protein called intrinsic factor.
People with pernicious anaemia produce antibodies that attack the gastric parietal cells so that not enough intrinsic factor is made. Without intrinsic factor vitamin B12 cannot be absorbed from the stomach. This deficiency causes anaemia because the body cannot produce fully functioning red blood cells, vital for carrying oxygen.
How common is it?
Pernicious anaemia is the most common cause of vitamin B12 deficiency in the UK, although accurate figures for how many people have the condition are hard to come by.
It is not know why some people produce the antibodies that destroy the stomach parietal cells.
However, the condition is more likely in older people over 60 and is more common in women than men.
You are more at risk of developing pernicious anaemia if you have another autoimmune condition such as Addison's disease or vitiligo - a condition that causes pale patches of skin to develop.
What are the symptoms of pernicious anaemia?
Symptoms vary between individual patients, but the Pernicious Anaemia Society says those most commonly reported are tiredness, lethargy, exhaustion, fatigue, weariness and loss of memory.
Other symptoms associated with vitamin B12 deficiency include headache, tinnitus, depression, mouth ulcers and a change in the way you walk or move around.
How is pernicious anaemia diagnosed?
If your GP suspects that you have vitamin B12 deficiency anaemia, they will carry out a blood test to confirm the diagnosis. This involves taking a sample of blood from your arm and measuring all the different types of blood cells in the sample.
If the test results indicate vitamin B12 deficiency, your GP may recommend a further test called the intrinsic factor antibody test which looks for the antibodies which attack the stomach cells. If a patient tests positive for the antibodies, he or she will be diagnosed with pernicious anaemia.
How is pernicious anaemia treated?
The NHS recommends that patients with pernicious anaemia are given injections of vitamin B12 in the form of a substance known as hydroxocobalamin. Injections are given every three months for the rest of the patient's life.
After injections start, further blood tests will be carried out to ensure that your body's vitamin B12 levels are starting to rise and that they reach a normal level.