ANAEMIA - a patient's guide
- Anaemia is a reduction in red blood cells (haemoglobin)
- A person is considered anaemic when their haemoglobin levels fall below normal
- There are many different causes of anaemia
- The most common cause is iron deficiency (there are many causes of iron deficiency)
- Anaemia can also indicate a serious disease such as cancer
- Diagnosis of anaemia involves blood tests to determine the cause - this may include tests of the bowel (endoscopyand/or colonoscopy), to find the source of blood loss. A bone marrow test may be needed in some cases.
Anaemia is a significant reduction in blood red blood cell (haemoglobin) levels.
A person is considered anaemic when the blood haemoglobin level is below the normal range for their age and sex.
Haemoglobin carries oxygen in the blood. The normal haemoglobin for a woman ranges from 115 to 160 g/l and for a man, 135 to 180 g/l.
There are many causes and several types of anaemia - it can indicate an underlying illness or may mean the person's diet is deficient in iron (found in red meat).
Tests should be done before treatment, so that the cause can be identified.
It is important to realise that iron deficiency is not a full diagnosis in itself, and a cause for the iron loss should be sought. Your doctor will be able to discuss what tests are most appropriate. The tests may include a search of the bowel to find a source of blood loss (e.g. an ulcer or bowel cancer).
What are the symptoms of anaemia?
Usually mild anaemia causes very few or minimal symptoms and may only be discovered on a blood test.
As the haemoglobin falls (usually to below 80 g/l), the individual looks pale and can be short of breath on exercise, with a pounding heart and dizziness on standing.
As the anaemia becomes more severe, the heart and other vital organs can suffer from lack of oxygen, resulting in severe consequences, especially if there is already impaired blood supply, such as occurs in angina.
Sometimes there are symptoms of the illness which is causing the anaemia, for example a change in bowel function (blood loss from bowel cancer), or very heavy prolonged periods.
Causes of anaemia
The cause of anaemia should always be investigated, as it may be a sign of a serious underlying diagnosis. This process requires a careful history and clinical examination as well as further investigations including blood tests, and in cases where the cause is still not clear, a bone marrow examination.
Overview of the different types of anaemia;
1-Decreased Red Cell Production
- Iron deficiency, anaemia of chronic disease, kidney failure
- Megaloblastic anaemia from B12 or folate deficiency
- Bone marrow disease : aplastic anaemia, leukaemia; or other cancers
- Toxic injury e.g. radiotherapy or chemotherapy
2. Increased Red Cell Destruction
- Blood loss: acute or chronic
- Haemolysis (intrinsic - this involves the red cells breaking down) - this can occur from genetic mutations in the red cell membrane proteins, the haemoglobin molecule or the chemicals needed to maintain the quality of the cell throughout its life.
- Haemolysis (extrinsic) - this can be secondary to red cell antibodies, or red cell damage from extensive clotting in the blood vessels, severe burns, or from some infections, damage from mechanical cardiac valves or from enlarged spleens.
Iron deficiency, the most common cause of anaemia in the world with over a billion people affected, is diagnosed by blood tests including serum iron studies. Treatment is important in severe cases, but also in infants and in early pregnancy where the consequences can be important. If there is no clear cause in an adult, bleeding from the bowel should be excluded in case there is an underlying cancer. Parasites such as hookworm in the bowel can also cause bleeding - these should be looked for in the stools of subjects from areas where this infestation occurs.
Anaemia of chronic disease
Anaemia of chronic disease occurs commonly in chronic inflammation such as rheumatoid arthritis, and infections such as tuberculosis and cancers. Certain chemicals (Interleukins and interferons) are produced in these conditions which mediate the immune or inflammatory response, and these can cause a number of symptoms such as weight loss, fatigue and malaise. They also block the absorption of iron in the bowel, and impair the movement of iron from storage cells to the developing red cells. The anaemia improves when the chronic disease is treated.
Folate lack occurs from dietary deficiency (common in the seriously ill or malnourished), from malabsorption (as in bowel disease) and from increased use or loss (as in pregnancy, haemolysis or kidney dialysis). Folate should be given to malnourished individuals and others at risk of deficiency, after checking the serum folate and B12 levels.
Vitamin B12 deficiency is most commonly due to pernicious anaemia, total or partial stomach surgery or other bowel causes. Injections should be given routinely in patients with those conditions to prevent or treat not only anaemia, but also damage to nerves.
Anaemia of renal disease is mainly due to a lack of the hormone erythropoietin. This hormone can be used to successfully treat this complication, and to improve the quality of life of these patients.
Autoimmune haemolytic anaemia occurs when the body makes antibodies that destroy red cells. This can occur with some infections or as part of autoimmune diseases such as systemic lupus erythematosis. The antibodies can make transfusions difficult. Treatments include immune suppression or removal of the spleen in difficult cases.
Hypersplenism can cause anaemia from increased pooling and decreased survival of red cells. This occurs in patients with large spleens, such as those with chronic liver disease.
Alcoholism produces anaemia in several ways, including a direct toxic effect on heme synthesis, folate deficiency from poor nutrition, hypersplenism (overactive spleen) and iron deficiency if bleeding from the bowel occurs.
Sickle cell anaemia occurs in black Americans, Africans and others from Saudi Arabia, India, and Southern Europe. The red cells precipitate (clot) in small blood vessels and can cause splenic, bone or liver destruction, and chronic skin ulcers.
Thalassemias are genetic disorders, which produce a reduction in the globin part of haemoglobin. They occur in a broad geographical region from the Mediterranean through the Middle East and India to South East Asia, and in other populations including Maori and Polynesians. Genetic counselling and pre-natal diagnosis should be performed in those at risk to prevent the severe forms that can result in severe maternal complications (alpha-thalassemia) or lifelong transfusions (beta-thalassemia major). Milder forms in carriers can be difficult to differentiate from mild iron deficiency.