Anaemia occurs when the concentration of the body’s red blood cells, or the oxygen-carrying pigment contained in them (haemoglobin) falls below normal levels. Anaemia isn’t a condition itself, but is often a sign of an underlying medical disorder.
What causes anaemia?
Broadly speaking, there are 3 main causes of anaemia.
- Blood loss, for example, through heavy menstrual periods or gastrointestinal bleeding from an ulcer.
- Defective red blood cell production, which can result from nutritional or vitamin deficiencies or a chronic illness where the bone marrow does not work properly.
- Red blood cell destruction, which may be due to hereditary factors, some autoimmune disorders, or as a side effect of some drugs.
Signs and symptoms of anaemia
A person with anaemia often looks very pale and may also experience:
- fatigue, tiredness, lack of energy;
- weak and rapid pulse;
- dizziness, particularly when the person stands up;
- shortness of breath, particularly on exertion;
- racing heart or palpitations, particularly on exertion;
- spoon-shaped nails (koilonychia) – where the nail looks like it is scooped out – and can hold a drop of liquid. ‘Spoon nails’ are a sign of iron-deficiency anaemia;
- altered taste;
- cravings for non-food substances, such as ice or dirt; or
- tinnitus (ringing in the ears).
However, anaemia may not be obvious, particularly in young people or people in otherwise good health, whose haemoglobin levels may fall significantly without any symptoms showing at all. In other cases symptoms may develop slowly over months or years.
Tests and diagnosis of anaemia
Anaemia can be detected on a full blood count – a routine blood test which measures the different types of cells in your bloodstream. For many people, a routine screening blood test will be the first signal that they have anaemia.
Indications of anaemia are:
- Low red cell count – low number of red blood cells
- Low haematocrit (percentage of red blood cells relative to the total blood volume)
- Low haemoglobin in your red blood cells.
Normal red cell count:
- Men – 4.5 – 6.5 x 1012/L
- Women – 3.8 – 5.8 x 1012/L.
Normal haematocrit is:
- Men – 40-54%
- Women – 37-47%
Normal levels of haemoglobin are:
- Men – 135-175 g/L
- Women – 115-165 g/L.
If results from a full blood count indicate you have anaemia, there are further blood tests and blood examination that can be done to determine the cause of your anaemia and/or the type of anaemia. The laboratory will look at the colour, size and shape of your red cells for any abnormal features.
To find out the cause of your anaemia, your doctor may suggest iron studies. Iron studies are a group of tests done on one blood sample. They measure iron levels in your blood, and also ferritin and transferrin – 2 substances involved in transporting and storing iron.
If your doctor suspects you have gastrointestinal bleeding, they may suggest a faecal occult blood test, which looks for blood in your stool.
Vitamin B12 is another test that may be ordered in the investigation of anaemia. Vitamin B12 is needed to make red blood cells. Normal levels are between 120 and 680 pmol/L.
Other tests that may be done include liver function tests.
The body needs iron for red blood cell production. But if there isn’t enough iron, due to iron being lost from the body or not enough being consumed, then iron-deficiency anaemia will result.
Iron-deficiency anaemia is the most common form of anaemia worldwide and is common in Australia.
People most at risk include:
- women of child-bearing age (because of monthly blood loss from their periods);
- pregnant women (because of the drain on their iron stores by the developing baby);
- breast-fed infants who are just starting a full diet (because at this stage of development the baby’s stores of iron from the mother are beginning to be depleted and there may not be enough iron in the milk); and
- people with restricted diets. For those with vegetarian or vegan diets it is important to consume iron-containing foods such as lentils, dried beans and peas, wholegrain cereals (especially iron-fortified breakfast cereals), nuts and green leafy vegetables;
- people with intestinal disorders, such as coeliac disease, which affect their ability to absorb nutrients.
In women who have gone through the menopause, and adult men, very little iron is lost under normal circumstances, therefore iron deficiency may indicate that ongoing gastrointestinal bleeding, perhaps in only microscopic amounts, is present. For this reason, iron deficiency should be investigated thoroughly in these groups in case there is blood being lost from the gastrointestinal system, e.g. through NSAID (anti-inflammatory) use or undiagnosed cancer.
Other forms of anaemia
Other forms of anaemia, which are less common, include the following.
- Haemolytic anaemia, where red blood cells are destroyed faster than the body can produce new ones. This can result from autoimmune conditions such as systemic lupus erythematosus, or some types of cancer such as lymphoma, or the use of medications that can destroy red blood cells (for example, methyldopa). While symptoms are similar to those of other types of anaemia, some people can experience a ‘haemolytic crisis’ where blood cells are destroyed rapidly and suddenly, resulting in fever, chills, back and stomach pain and a sudden significant drop in blood pressure.
- Pernicious anaemia, caused by the intestine’s inability to adequately absorb vitamin B12 from food. Because a deficiency of vitamin B12 can lead to damage to the nervous system, a person with pernicious anaemia must take B12 supplements for life. These are usually given by injection.
- Folic acid deficiency anaemia, caused by a lack of folic acid (known as folate or vitamin B9) in the diet. Folate is found in dark green leafy vegetables, cereals, legumes and fresh fruit. Because the body stores only a small amount of folate, a person who doesn’t eat much of these foods may develop a deficiency within a few months. Treatment consists of rectifying the diet and taking supplements if needed.
- Bone marrow failure, which may be due to leukaemia or other cancer-like diseases infiltrating the bone marrow and affecting the production of red cells. Some medicines and treatments, such as chemotherapy agents or radiotherapy, can also affect the bone marrow’s ability to produce red cells.
- Anaemia of chronic disease — it is common for people with significant chronic (longstanding) disease of any sort (for example, kidney failure) to have mild anaemia.
- Aplastic anaemia — a defect in red blood cell production by the bone marrow (white cell and platelet production is also affected). Some cases have no known cause but others result from problems with the immune system.
- Sickle cell anaemia and thalassaemia — disorders of haemoglobin. Sickle-cell anaemia is characterised by abnormally shaped red blood cells which block and damage small blood vessels, causing blocked blood vessels and eventually organ damage. It is more common in people of African, Mediterranean or Asian descent than Caucasians. Thalassaemias are a range of genetic disorders resulting from errors in the production of the amino acids that make up haemoglobin: anaemia is a common symptom of these disorders.
Some factors put you at increased risk of anaemia, including:
- a diet lacking in vitamin B12 and folate
- being vegetarian or vegan
- disorders that affect absorption, such as coeliac disease
- pregnancy and breastfeeding
- menstruation, especially if you have heavy periods
- donating blood frequently
- being older than 65, especially people in aged care
- being an indigenous Australian
- being adolescent, especially during growth spurts
- infants and children, especially if not eating a healthy diet
- low-birth weight infants or premature infants
- having had weight-loss surgery (some types).
Treatment of anaemia
If you have anaemia your treatment will depend on its cause.
If you are deficient in iron, your doctor may recommend a supplement. Pregnant women may also need to take a supplement. However, you should only take iron supplements under the direction of your doctor. Iron supplements can be toxic, and even fatal, in large doses.
You can buy iron supplements from a health food store or pharmacy without a prescription. However, you should not rely on supplements at the expense of a good diet. Iron supplements are absorbed best if they are taken about 30 minutes before meals and taken with vitamin C. One tablet a day is usually enough — any more than this may not be absorbed by the intestine and may cause indigestion and constipation. You may notice that your stools turn a black colour if you are taking iron. This is a normal and harmless side effect.
Iron injections may be prescribed by a doctor if a person cannot take supplements or is very low on iron.
If you suspect that a child or adult has overdosed on iron tablets, ring your doctor or the Poisons Information Centre on 131 126.
Foods rich in iron
It’s important to eat foods rich in iron regularly. Australians get most of their iron from wholegrain cereals, meats, fish and poultry.
Iron in food comes in 2 forms: haem iron and non-haem iron. Haem iron is only found in meat and fish and it’s easily absorbed. The iron found in plant foods is non-haem iron and it’s more difficult to absorb than haem iron. The absorption of non-haem iron from plant foods can be improved by consuming vitamin C at the same time.
Some dietary components can adversely affect the absorption of both haem and non-haem iron – for example, phytates (found in legumes, rice and grains) and calcium and zinc.
Enhancing iron absorption
You can improve how much iron you absorb from food by eating foods rich in vitamin C with your iron-containing foods, avoiding drinking tea or coffee with or after iron-rich foods, and by cooking plant foods.
To prevent iron-deficiency and folic acid deficiency anaemias, you should make sure that your diet includes foods such as lean red meat, fruit, whole-grain bread, cereals, beans, fish, nuts, and green vegetables.
In other cases of anaemia, diet and medication aren’t enough to make a person get better. In these situations, the infusion of blood or blood components directly into the bloodstream may be needed.
Untreated iron-deficiency anaemia can cause serious health problems. These include heart problems (as the heart works harder to compensate for the lack of haemoglobin or red blood cells), depression, increased risk of infections and serious fatigue.
A woman’s iron requirements increase when pregnant, especially towards the end of the pregnancy. Many women will need iron supplements during pregnancy. Untreated anaemia in pregnancy may lead to premature birth or a low birth weight for your baby, or you may need a blood transfusion after the birth.
What healthcare professionals are involved in diagnosing and treating anaemia?
Your General Practitioner (GP) is the best place to start if you think you may be anaemic. They can order blood tests for you to determine whether you are anaemic and refer you for further investigations to find the cause of the anaemia.
Your blood tests will be analysed at a pathology lab and the results will determine if any further investigations are needed.
Depending on the cause of your anaemia, your GP may refer you to a Haematologist – a specialist who deals with the treatment of blood disorders and diseases, a Gastroenterologist – who can determine if you have any bowel disorders that are causing blood loss or preventing you from absorbing iron efficiently, or a Dietitian – who can help you devise a diet to meet your needs for iron and other nutrients.