Iron deficiency anaemia is a condition where a lack of iron in the body leads to a reduction in the number of red blood cells.
Iron is used to produce red blood cells, which help store and carry oxygen in the blood. If you have fewer red blood cells than is normal, your organs and tissues won't get as much oxygen as they usually would.
There are several different types of anaemia, and each one has a different cause. Iron deficiency anaemia is the most common type.
In women of reproductive age, heavy periods and pregnancy are the most common causes of iron deficiency anaemia as your body needs extra iron for your baby during pregnancy.
Unless you're pregnant, it's rare for iron deficiency anaemia to be caused just by a lack of iron in your diet. However, if you do lack dietary iron, it may mean you're more likely to develop anaemia than if you have one of the problems mentioned above.
If iron deficiency anaemia is left untreated, it can make you more susceptible to illness and infection, as a lack of iron affects the body's natural defence system (the immune system).
Severe iron deficiency anaemia may increase your risk of developing complications that affect the heart or lungs, such as an abnormally fast heartbeat heart failure, where your heart is unable to pump enough blood around your body at the right pressure.
Pregnant women with severe or untreated anaemia also have a higher risk of complications before and after birth.
If your GP thinks your medication is causing gastrointestinal bleeding, they can prescribe a less harmful medicine. However, don't stop taking a medicine you've been prescribed unless your GP advises you to.
The acid in your stomach, which helps your body digest food, can sometimes eat into your stomach lining. When this happens, the acid forms an open sore (an ulcer). This is also known as a stomach ulcer or a peptic ulcer.
Stomach ulcers can cause the stomach lining to bleed, which can lead to anaemia. In some cases, the bleeding can cause you to pass blood in your stools. However, if the ulcer bleeds slowly, you may not have any symptoms.
In a few cases, gastrointestinal bleeding can be caused by cancer, usually bowel cancer.
When trying to establish the cause of anaemia, your GP will check for possible signs of cancer.
If your GP suspects cancer, you'll be referred to a gastroenterologist (a specialist in treating digestive conditions) for a more thorough examination. This means that if cancer is found, it can be treated as quickly as possible.
If you're 60 years old or over and have iron deficiency anaemia, your GP should refer you to a specialist to rule out bowel cancer. Your appointment with the specialist should be within two weeks of your GP referring you.
Gastrointestinal bleeding can also be caused by a condition called angiodysplasia. This is the result of abnormal, fragile superficial blood vessels in the gastrointestinal tract, which can cause bleeding.
A simple blood test can usually confirm the diagnosis.
Your GP may also carry out a physical examination and ask you a number of questions to help determine the cause of your anaemia.
To diagnose iron deficiency anaemia, a blood sample is taken from a vein in your arm and a full blood count is made. This means all the different types of blood cells in the sample will be measured.
If you have anaemia:
your levels of haemoglobin – a substance that transports oxygen – will be lower than normal
you'll have fewer red blood cells, which contain haemoglobin, than normal
your red blood cells may be smaller and paler than usual
Your GP may also test for a substance called ferritin, a protein that stores iron. If your ferritin levels are low, it means there isn't much iron stored in your body and you may have iron deficiency anaemia.
If your GP thinks your anaemia may be the result of a vitamin B12 and folate deficiency, the levels of these substances may be tested. Folate works with vitamin B12 to help your body produce red blood cells.
To determine the underlying cause of your anaemia, your GP may ask questions about your lifestyle and medical history. For example, they may ask you about:
your diet – to see what you typically eat and whether this includes any iron-rich foods
any medicines you take – to see if you've been regularly taking a type of medicine that can cause bleeding from the stomach and intestines (gastrointestinal bleeding), such as aspirin
your menstrual pattern – if you're a woman, your GP may ask if you've been experiencing particularly heavy periods
your family history – you'll be asked if your immediate family has anaemia or a history of gastrointestinal bleeding or blood disorders
blood donation – your GP may ask if you regularly donate blood
other medical conditions – your GP may ask if you've recently had another illness or experienced other symptoms, such as weight loss
Iron deficiency anaemia is common during pregnancy. If you're pregnant, your GP will usually only look for an alternative cause if a blood test has identified a particularly low haemoglobin level, or if your symptoms or medical history suggest your anaemia may be caused by something else.
A physical examination will usually only be needed if the cause of your iron anaemia deficiency hasn't been identified by examining your medical history and asking you about your symptoms.
In such cases, your GP may:
examine your stomach (abdomen) to check for any physical signs of gastrointestinal bleeding
look for signs of heart failure, such as swollen ankles – heart failure can have some similar symptoms to iron deficiency anaemia
Two other possible types of physical examination you may have are explained below.
A rectal examination is usually only needed if you're bleeding from your bottom. It's a common procedure that can help your GP find out if there's something in your gastrointestinal tract that's causing bleeding.
Your GP will insert a lubricated gloved finger into your bottom to feel for any abnormalities.
A rectal examination isn't something to be embarrassed about, as it's a procedure your GP will be used to doing. It shouldn't cause significant pain, but it may cause some slight discomfort – this will only last for a minute.
Women may have a pelvic examination if their GP thinks heavy menstrual bleeding (menorrhagia) may be the cause of their anaemia.
During a pelvic examination, your GP will examine your vulva and labia (external sex organs) for signs of bleeding or infection.
They may also examine you internally. This will involve your GP inserting lubricated gloved fingers into your vagina to feel whether your womb (uterus) is tender or enlarged.
A pelvic examination won't be carried out without your consent (permission), and you can choose to have someone with you.
Referral to a specialist
In some cases, your GP may refer you to a gastroenterologist, a specialist in treating digestive conditions. They'll carry out a more thorough examination.
For example, you may be referred to a gastroenterologist if your GP can't identify a cause and you have a particularly low haemoglobin level, or if your GP thinks there's a possibility your symptoms could be caused by bowel cancer, although this is unlikely.
If you're a woman with heavy periods, you may be referred to a gynaecologist if you don't respond to treatment with iron supplements.
Treating iron deficiency anaemia
Treatment for iron deficiency anaemia usually involves taking iron supplements and changing your diet to increase your iron levels, as well as treating the underlying cause.
Your GP will prescribe an iron supplement to restore the iron missing from your body. The most commonly prescribed supplement is ferrous sulphate, which is taken as a tablet, usually twice a day.
Some people can experience side effects when taking iron supplements, including:
dried fruit, such as dried apricots, prunes and raisins
Your diet should include foods from all the major food groups to ensure it's healthy and balanced. In particular, food and drink containing vitamin C are important as vitamin C helps your body absorb iron.
However, consuming large amounts of some foods and drinks, as well as certain medicines, may make it harder for your body to absorb iron. These include:
wholegrain cereals – although wholegrains are a good source of iron themselves, they contain phytic acid, which can stop your body absorbing iron from other foods and pills
You may be referred to a nutrition specialist called a dietitian if you're finding it difficult to include iron in your diet. They'll be able to give you detailed, personalised advice about how you can improve your diet.
Treating the underlying cause
Your GP will also need to ensure the underlying cause of your anaemia is treated so it doesn't happen again.
Your GP will ask you to return two to four weeks after you've started taking iron supplements to check how well you've responded to the treatment. You'll have a blood test to check your haemoglobin levels.
If your blood test results show an improvement, you'll be asked to continue taking iron supplements and return in two to four months for another blood test.
Once your haemoglobin levels and red blood cells are normal, your GP will usually recommend continuing to take iron supplements for three months to help build up the iron levels in your body.
After this, you should be able to stop taking the supplements, depending on the cause of your iron deficiency anaemia. Your condition will be monitored every three months over the course of a year, and again a year later.
Sometimes after a person's iron levels have been replenished, they start to fall again.
This could happen if you don't get enough iron in your diet, you're pregnant, or you have consistently heavy periods.
In such cases, you may be prescribed an ongoing iron supplement to help stop your anaemia returning. This will usually be a tablet, which you'll have to take once a day.
If treatment is ineffective
If your iron levels don't improve, your GP will ask how regularly you've been taking your iron supplements.
Some people are put off taking the medication because of the side effects. However, your condition won't improve if you don't take the supplements.
If you've been taking the supplements as prescribed and your iron levels still haven't improved, your GP may refer you to a specialist for an assessment.
Complications of iron deficiency anaemia
Iron deficiency anaemia rarely causes serious or long-term complications, although some people with the condition find it affects their daily life.
Some common complications are outlined below.
Iron deficiency anaemia can make you feel tired and lacking in energy (lethargic). This may result in you being less productive at work, and you may find it difficult to stay awake or not feel able to exercise regularly.
Increased risk of infections
Research has shown iron deficiency anaemia can affect your immune system – the body's natural defence system. This increases your vulnerability to infection.
Heart and lung problems
Adults with severe anaemia may be at risk of developing complications that affect their heart or lungs.
For example, you may develop heart failure, where the heart fails to pump enough blood around your body at the right pressure.
Pregnant women with severe anaemia have an increased risk of developing complications, particularly during and after birth.
Research suggests babies born to mothers who have untreated anaemia are more likely to:
be born prematurely – before the 37th week of pregnancy
have a low birth weight
have problems with iron levels themselves
do less well in mental ability tests
Restless legs syndrome
Some cases of restless legs syndrome are thought to be caused by iron deficiency anaemia. Doctors often refer to this as secondary restless legs syndrome.
Restless legs syndrome is a common condition that affects the nervous system, and causes an overwhelming, irresistible urge to move the legs. It also causes an unpleasant feeling in the feet, calves and thighs.
Restless legs syndrome caused by iron deficiency anaemia can usually be treated with iron supplements.