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In the second part of our autoimmune disease series, we focus on pernicious anaemia, which is the most common cause of a vitamin B12 deficiency in the UK, explaining what it is and how to test for it.
Red blood cells contain haemoglobin, an iron-rich protein that gives the blood its red colour and carries oxygen around the body. Anaemia is a condition that arises when there are a low number of red blood cells or if there isn’t enough haemoglobin within the red blood cells. Symptoms of anaemia include extreme fatigue, lethargy, feeling faint, breathlessness and pale skin. There are 3 main causes of anaemia: blood loss, a lack of red cell production and high rates of red blood cell destruction. Although there are many different types of anaemia and many different conditions that can cause anaemia, some types can be prevented and corrected through eating a well-balanced diet. A lack of iron, vitamin B9 (folate) and vitamin B12 can all cause anaemia.
Vitamin B12 is a nutrient that is used in many of the body's processes including tissue and cell repair, energy and red blood cell production and the functioning of nerves and DNA. B12 is found mostly in animal proteins such as meat, fish, milk and eggs, as well as some fortified cereals and yeast extracts such as marmite. The body has a store of vitamin B12 in the liver so can often manage for a few years with these reserves if not provided with B12 from an outside source, however, eventually, these reserves will run out too. Those who are vegetarian or vegan are at a greater risk of having a vitamin B12 deficiency as B12 is found mostly in animal products.
Low levels of vitamin B12 can cause red blood cells to be large and misshapen which affects their oxygen-carrying capacity, causing anaemia and associated symptoms. Vitamin B12 deficiency anaemia occurs when a lack of vitamin B12 causes the production of abnormally large red blood cells that can't function properly. There are many different causes of a vitamin B12 deficiency including dietary deficiencies and conditions that affect absorption of the vitamin from the small intestine such as surgery, certain drugs and digestive disorders (coeliac disease, Crohn’s disease). However, the most common cause of vitamin B12 deficiency in the UK is pernicious anaemia.
Pernicious anaemia is an autoimmune condition that affects the stomach. In the stomach, vitamin B12 is combined with a protein called intrinsic factor. The formation of this complex is necessary for the absorption of vitamin B12 in the small intestine. In those with pernicious anaemia, their immune system attacks the parietal cells in the stomach that produce the intrinsic factor, meaning they are unable to absorb vitamin B12. The cause of pernicious anaemia is unknown, however, it is more common in women aged over 60, in people with a family history of the disease and those with other autoimmune conditions .
Pernicious anaemia stops the body from making enough healthy red blood cells, as without enough intrinsic factor, the body cannot absorb vitamin B12 from the diet and cannot produce enough normal red blood cells, leading to anaemia. The lack of healthy red blood cells brings about many of the symptoms associated with anaemia including fatigue, breathlessness and lethargy. Anaemia caused by a vitamin B12 deficiency may also present symptoms such as mouth ulcers, pins and needles (paraesthesia) and a sore, red tongue .
If you are experiencing symptoms of anaemia, our anaemia check is a great initial test to help establish whether you could be anaemic and what the likely causes are. Tests include a full blood count, iron status including ferritin and active B12. If your vitamin B12 levels are very low, one of our doctors will comment on your result and may recommend further tests such as a methylmalonic acid (MMA) or intrinsic factor antibodies test to investigate further and identify whether pernicious anaemia could be the cause of your low levels.
Treatment of a vitamin B12 deficiency differs depending on the cause of low levels. If they are because of a dietary deficiency, vitamin B12 supplements can help to improve levels. However, pernicious anaemia usually requires vitamin B12 injections. If left untreated, pernicious anaemia can lead to a number of health issues including nerve damage, neurological problems such as memory loss and digestive tract problems .
Testing your vitamin B12 level is super easy with Medichecks, receive your results in a matter of days after posting your sample to the laboratory and rest assured if your levels are low, one of our doctors is on hand to advise further.
 nhs.uk. (2019). Causes. [online] Available at: https://www.nhs.uk/conditions/vitamin-b12-or-folate-deficiency-anaemia/causes/ [Accessed 14 Feb. 2019].
 Nhsinform.scot. (2019). Vitamin B12 or folate deficiency anaemia symptoms and treatments. [online] Available at: https://www.nhsinform.scot/illnesses-and-conditions/nutritional/vitamin-b12-or-folate-deficiency-anaemia [Accessed 14 Feb. 2019].
 Nhlbi.nih.gov. (2019). Pernicious Anemia | National Heart, Lung, and Blood Institute (NHLBI). [online] Available at: https://www.nhlbi.nih.gov/health-topics/pernicious-anemia [Accessed 14 Feb. 2019].