Anaemia means that you have fewer red blood cells than normal or you have less haemoglobin than normal in each red blood cell. In either case, a reduced amount of oxygen is carried around in the bloodstream.
- Common symptoms are due to the reduced amount of oxygen in the body. These include tiredness, having little energy (lethargy), feeling faint and becoming easily breathless.
- Less common symptoms include headaches, a 'thumping heart' (palpitations), altered taste, and ringing in the ears (tinnitus).
- You may look pale.
- Various other symptoms may develop, depending on the underlying cause of the anaemia.
A simple blood test can measure the amount of haemoglobin in your blood and count the number of red blood cells per millilitre (ml). Although this test can confirm that you are anaemic, it does not identify the cause of your anaemia.
Sometimes the underlying cause is obvious. For example, anaemia is common in pregnancy and in women who have heavy menstrual periods. In these situations, no further tests may be needed and treatment with iron tablets may be advised. However, the cause of the anaemia may not be clear and so further tests may be advised.
Some causes of anaemia are more serious than others and it is important to find the reason for anaemia. The treatment of anaemia depends on the underlying cause. For many people this may simply be iron tablets. For others it may be a course of vitamins or other more complex treatments.
What are the causes of anaemia?
Lack of iron is the most common cause of anaemia in the UK. This is called iron-deficiency anaemia. If you eat a normal balanced diet, it usually contains enough iron.
The following are some reasons that may lead to a lack of iron and result in iron-deficiency anaemia:
- Pregnancy or childhood growth spurts. These are times when you need more iron than usual. The amount of iron that you eat during these times may not be enough.
- Heavy menstrual periods. The amount of iron that you eat may not be enough to replace the amount that you lose from heavy periods.
- Poor absorption of iron. This may occur with some gut (intestinal) diseases - for example, coeliac disease and Crohn's disease.
- Bleeding from the gut (intestines). Some conditions of the gut can bleed enough to cause anaemia. You may not be aware of losing blood this way. The bleeding may be slow or intermittent and you can pass blood out with your stools (faeces) without noticing.
- If you eat a poor or restricted diet. Your diet may not contain enough iron.
There are many other causes of anaemia. These include the following:
Lack of certain vitamins such as folic acid and vitamin B12.
Bone marrow problems and leukaemia are uncommon; however, they can cause anaemia.
Further reading and references
Guidelines for the Diagnosis and Management of Adult Aplastic Anaemia; British Committee for Standards in Haematology (2015)
Erythropoiesis-stimulating agents in the treatment of anaemia in cancer patients: ESMO Clinical Practice Guidelines for use; European Society for Medical Oncology (2010)
Clinical Practice Guideline Anaemia of Chronic Kidney Disease; The Renal Association, 2017 - updated February 2020
Anaemia - iron deficiency; NICE CKS, February 2013 (UK access only)