Iron deficiency anaemia

Iron deficiency anaemia happens when your body doesn't have enough iron, and so you end up with fewer red blood cells than you should have.

Your body uses iron to make red blood cells. These cells store oxygen and carry it around in your blood. When you have fewer of them than normal, your organs and tissues don't get as much oxygen as they usually would.

There are several types of anaemia, and each has its own cause. Iron deficiency anaemia is the most common one.

Some other types are caused by a lack of vitamin B12 or folate in the body, which is known as vitamin B12 and folate deficiency anaemia.

Many people with iron deficiency anaemia have only a few symptoms. How strong they are depends largely on how quickly the anaemia develops.

You may notice symptoms straight away. Or they may come on slowly, if a long-term problem such as a stomach ulcer is causing your anaemia.

The most common symptoms are:

• tiredness and lack of energy (lethargy)
• shortness of breath
• noticeable heartbeats (heart palpitations)
• a pale complexion

Less common symptoms are:

• headache
• hearing sounds that come from inside the body, rather than from an outside source (tinnitus)
• an altered sense of taste
• feeling itchy
• a sore or abnormally smooth tongue
• hair loss
• a desire to eat non-food items, such as ice, paper or clay (pica)
• difficulty swallowing (dysphagia)
• painful open sores (ulcers) on the corners of your mouth
• spoon-shaped nails

If you have symptoms of iron deficiency anaemia, see your doctor. A simple blood test should be enough for them to diagnose the condition.

Many things can lead to a lack of iron in the body, and the cause is different depending on who you are. In men and in women who have been through the menopause, the most common cause of iron deficiency anaemia is bleeding in the stomach and intestines. A stomach ulcer, stomach cancer or bowel cancer can cause this kind of bleeding, and so can taking non-steroidal anti-inflammatory drugs (NSAIDs).

In women of reproductive age, heavy periods and pregnancy are the most common causes. During pregnancy your body needs extra iron for your baby.

Unless you're pregnant, it's rare for iron deficiency anaemia to be caused just by a lack of iron in your diet. But if you do lack iron in your diet, you may be more likely to develop anaemia than if you had one of the problems mentioned above.

Iron deficiency anaemia is treated with iron supplements, which bring up the low iron levels in your body. This usually works well, and the condition rarely causes long-term problems.

Your doctor will want to check you every few months. The aim is to see that the treatment is working and that your iron levels have returned to normal.

The cause behind the anaemia needs to be treated too, so it doesn't come back. You may also be advised to eat more iron in your diet.

Good sources of iron include:

• dark-green leafy vegetables, such as watercress and curly kale
• iron-fortified cereals or bread
• brown rice
• pulses and beans
• nuts and seeds
• meat, fish and tofu
• eggs
• dried fruit, such as dried apricots, prunes and raisins

If iron deficiency anaemia is left untreated, you can become more likely to catch illnesses and infections. A lack of iron affects the body's natural defence system (the immune system).

Severe iron deficiency anaemia may also raise your risk of complications affecting the heart or lungs. One is an abnormally fast heartbeat (tachycardia). Another is 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.

Iron deficiency anaemia happens when your body doesn't have enough iron, so it makes fewer red blood cells. Those cells carry oxygen around the body.

A lack of iron can come from several causes. The most common ones are outlined below.

For women who are still having periods, monthly bleeding is the most common cause of iron deficiency anaemia. It's usually only women with heavy periods who develop it. If you bleed heavily over several menstrual cycles in a row, the condition is called menorrhagia.

Many women also develop iron deficiency during pregnancy. Your body needs extra iron then, so that your baby gets enough blood supply and receives the oxygen and nutrients it needs.

Some pregnant women need an iron supplement, while others may only need to increase the amount of iron in their diet.

The gastrointestinal tract is the part of your body that digests food. It includes the stomach and the intestines.

Bleeding in this tract is the most common cause of iron deficiency anaemia in men, and also in women who have been through the menopause (when monthly periods stop). Most people with gastrointestinal bleeding don't see any obvious blood in their stools, and their bowel habits don't change either.

Some causes of gastrointestinal bleeding are described below.

Non-steroidal anti-inflammatory drugs (NSAIDs) can cause bleeding in the stomach, and that is one way iron deficiency anaemia can start. Ibuprofen and aspirin are two NSAIDs that doctors prescribe often.

If your doctor thinks one of your medicines is causing bleeding in the gut, they can prescribe a less harmful one instead. But don't stop taking a medicine you've been prescribed unless your doctor tells you to.

The acid in your stomach helps your body digest food, but it can sometimes eat into the stomach lining. When that happens, the acid leaves an open sore. This is called a stomach ulcer, or a peptic ulcer.

A stomach ulcer can make the stomach lining bleed, and that bleeding can lead to anaemia. Sometimes the bleeding is heavy enough that you vomit blood or pass blood in your stools. But if the ulcer bleeds slowly, you may notice no symptoms at all.

In a few cases, gastrointestinal bleeding can be caused by cancer, usually stomach cancer or bowel cancer. When your doctor is trying to find the cause of your anaemia, they will check for possible signs of cancer.

If the doctor 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 doctor should refer you to a specialist to rule out bowel cancer.

Bleeding in the gut can also come from angiodysplasia. In this condition, the blood vessels near the surface of the gastrointestinal tract are abnormal and fragile, and they can bleed.

People with chronic kidney disease (CKD) often develop iron deficiency anaemia.

Most people with CKD who have iron deficiency anaemia will be given iron supplement injections. Daily tablets may be tried first, though.

You can read more about how anaemia is treated in people with CKD on the website of the National Institute for Health and Care Excellence (NICE).

Other conditions or actions that cause blood loss can also lead to iron deficiency anaemia. These include:

• inflammatory bowel disease, a condition that causes redness and swelling (inflammation) in the digestive system, such as Crohn's disease and ulcerative colitis
• oesophagitis, which is inflammation of the gullet (oesophagus) caused by stomach acid leaking through it
• schistosomiasis, an infection caused by parasites, mainly found in sub-Saharan Africa
• blood donation, because donating a large amount of blood may lead to anaemia
• trauma, since a serious accident, such as a car crash, may cause you to lose a large amount of blood
• nosebleeds, as having regular nosebleeds may lead to anaemia, although this is rare
• haematuria (blood in your urine), but this rarely causes anaemia and may be a symptom of another condition

Malabsorption means your body can't take in iron from the food you eat, and it's another possible cause of iron deficiency anaemia.

This can happen if you have coeliac disease, a common digestive condition in which the body reacts badly to gluten. It can also happen after surgery to remove all or part of your stomach (gastrectomy).

Unless you're pregnant, iron deficiency anaemia is rarely caused only by a lack of iron in your diet. But if you also have any of the conditions mentioned above, not getting enough iron from food can raise your risk of developing anaemia.

Some studies suggest that vegetarians and vegans are more at risk of iron deficiency anaemia, because their diet has no meat. If you're vegetarian or vegan, you can still get enough iron from other foods, such as:

• beans
• nuts
• dried fruit, such as dried apricots
• wholegrains, such as brown rice
• fortified breakfast cereals
• soybean flour
• most dark-green leafy vegetables, such as watercress and curly kale

If you're pregnant, you may need to eat more iron-rich food during pregnancy to help prevent iron deficiency anaemia.

See a doctor if you notice symptoms of iron deficiency anaemia, such as tiredness, shortness of breath and heart palpitations.

A simple blood test can usually confirm the diagnosis. The doctor may also examine you and ask a number of questions, which helps to work out what is causing your anaemia.

To diagnose iron deficiency anaemia, a doctor takes a blood sample from a vein in your arm and does a full blood count. This means all the different types of blood cells in the sample are measured.

If you have anaemia:

• your haemoglobin (a substance that carries oxygen) will be lower than normal
• you'll have fewer red blood cells than normal, and these are the cells that contain haemoglobin
• your red blood cells may be smaller and paler than usual

Your doctor may also test for a substance called ferritin, a protein that stores iron. If your ferritin level is low, it means there isn't much iron stored in your body and you may have iron deficiency anaemia.

If your doctor thinks your anaemia may be caused by a vitamin B12 and folate deficiency, they may test the levels of these substances in your blood. Folate works with vitamin B12 to help your body make red blood cells.

Vitamin B12 and folate deficiency anaemia is more common in people over the age of 75.

To find the cause of your iron deficiency anaemia, your doctor may ask about your lifestyle and medical history. For example, they may ask about:

• your diet, to see what you usually eat and whether it 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 ibuprofen or aspirin
• your menstrual pattern, because if you're a woman, your doctor may ask if you've had particularly heavy periods
• your family history, because you'll be asked if your immediate family has anaemia or a history of gastrointestinal bleeding or blood disorders

Iron deficiency anaemia is common during pregnancy. If you're pregnant, your doctor will usually only look for another cause if a blood test has shown a particularly low haemoglobin level, or if your symptoms or medical history suggest something else may be causing your anaemia.

A physical examination is usually needed only when your medical history and your symptoms haven't shown what's causing your iron deficiency anaemia.

In that case, your doctor 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)

There are two other types of physical examination you may have, and they are explained below.

A rectal examination is usually only needed if you're bleeding from your bottom. It's a common procedure, and it can help your doctor find out whether something in your gastrointestinal tract is causing the bleeding.

Your doctor will gently insert a lubricated, gloved finger into your bottom to feel for any abnormalities.

There's no need to feel embarrassed about it, because doctors are used to doing this examination. It shouldn't cause significant pain, though you may feel some slight discomfort (this lasts only a minute).

A woman may have a pelvic examination if her doctor thinks heavy menstrual bleeding (menorrhagia) could be the cause of her iron deficiency anaemia.

During the examination, your doctor will look at your vulva and labia (the external sex organs) for signs of bleeding or infection.

They may also examine you internally. For this, the doctor inserts lubricated, gloved fingers into your vagina to feel whether your womb (uterus) is tender or enlarged.

An examination like this won't be carried out without your consent (permission), and you can choose to have someone with you.

Sometimes your doctor may send you to a gastroenterologist, a specialist in treating digestive conditions. They'll examine you more thoroughly.

You might be referred if your doctor can't find a cause for your iron deficiency anaemia and your haemoglobin level is particularly low. You might also be referred if your doctor thinks your symptoms could possibly be caused by stomach cancer or bowel cancer, although this is unlikely.

If you're a woman with heavy periods and you don't respond to treatment with iron supplements, you may be referred to a gynaecologist.

If you have iron deficiency anaemia, the treatment usually means taking iron supplements and changing what you eat so your iron levels go up. The doctor will also treat whatever is causing the problem in the first place.

Your doctor will prescribe an iron supplement to restore the iron missing from your body when you have iron deficiency anaemia. The one prescribed most often is ferrous sulphate, which you take as a tablet, usually twice a day.

Some people get side effects from iron supplements, including:

• abdominal (tummy) pain
• constipation or diarrhoea
• heartburn
• feeling sick
• black stools (faeces)

These side effects should settle down over time. If they trouble you, though, your doctor may suggest taking the tablets with food or shortly after eating.

Your doctor may also advise you to take only one or two tablets a day instead of three, if the side effects are hard to cope with.

If severe side effects mean you can't take ferrous sulphate, you may be given a different iron supplement called ferrous gluconate. It should cause fewer side effects because it contains a less concentrated dose of iron. But it may take longer for the iron levels in your body to be restored.

In a few cases, for example if you have chronic kidney disease (CKD), iron injections may be recommended instead of tablets.

As with all medicines, store iron supplements out of the reach of children. An overdose of iron supplements in a young child can be fatal.

If a lack of iron in your diet is thought to be adding to your iron deficiency anaemia, your doctor will tell you how to eat more iron.

Iron-rich foods include:

• dark-green leafy vegetables, such as watercress and curly kale
• iron-fortified cereals or bread
• brown rice
• pulses and beans
• nuts and seeds
• white and red meat
• fish
• tofu
• eggs
• dried fruit, such as dried apricots, prunes and raisins

Your diet should include foods from all the major food groups so that it stays healthy and balanced. Food and drink containing vitamin C matter particularly, because vitamin C helps your body absorb iron.

But large amounts of some foods and drinks, and certain medicines, may make it harder for your body to absorb iron. These include:

• tea and coffee
• calcium (found in dairy products, such as milk)
• antacids and proton pump inhibitors (PPIs), which are medicines used to relieve indigestion
• wholegrain cereals (wholegrains are a good source of iron themselves, but they contain phytic acid, which can stop your body absorbing iron from other foods and pills)

If you're finding it difficult to include iron in your diet, your doctor may refer you to a dietitian, a nutrition specialist. They can give you detailed, personalised advice on how to improve your diet.

Your doctor will also need to treat whatever is causing the iron deficiency anaemia, so that it doesn't come back.

For example, if non-steroidal anti-inflammatory drugs (NSAIDs) are causing bleeding in your stomach, your doctor may prescribe a different medicine to help lower the risk of stomach bleeding.

Heavy periods can be treated with medicine or, in particularly severe cases, with surgery.

Your doctor will ask you to come back two to four weeks after you start taking iron supplements. This visit is to see how well you're responding to the treatment, and you'll have a blood test to check your haemoglobin levels.

If the blood test shows an improvement, you'll be asked to keep taking the iron supplements and to come back in two to four months for another blood test.

Once your haemoglobin levels and red blood cells are normal, your doctor will usually recommend that you carry on with the supplements for three months. This helps build up the iron levels in your body.

After that, you should be able to stop the supplements, though this depends on the cause of your iron deficiency anaemia. Your condition will be checked every three months over the course of a year, and again a year later.

Sometimes a person's iron levels fall again after they have been built back up. This can happen if you don't get enough iron in your diet, if you're pregnant, or if you have heavy periods all the time.

If this applies to you, the doctor may prescribe an iron supplement to take on an ongoing basis, so your iron deficiency anaemia doesn't come back. It will usually be a tablet that you take once a day.

If your iron levels don't improve, your doctor will ask how regularly you've been taking your iron supplements.

Some people stop taking the medicine because of the side effects. But your condition won't get better 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 doctor may refer you to a specialist for an assessment.

Iron deficiency anaemia rarely causes serious or long-term complications, though some people find it affects their daily life.

A few of the more common complications are described below.

Iron deficiency anaemia can leave you feeling tired and short of energy (lethargic). You may get less done at work, find it hard to stay awake, or feel unable to exercise regularly.

Research has shown that iron deficiency anaemia can affect your immune system, which is the body's natural defence system. When that happens, you become more open to infection.

Adults with severe iron deficiency anaemia can develop complications that affect the heart or lungs. You may get tachycardia, which means an abnormally fast heartbeat. Or you may develop heart failure, where the heart can't pump enough blood around your body at the right pressure.

Women who have severe iron deficiency anaemia during pregnancy are more likely to run into complications, especially during and after the birth. Some may also develop postnatal depression, which some women experience after having a baby.

Research suggests that babies born to mothers with 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

Some cases of restless legs syndrome are thought to be caused by iron deficiency anaemia. Doctors often call this secondary restless legs syndrome.

Restless legs syndrome is a common condition that affects the nervous system. It brings an overwhelming, irresistible urge to move the legs, along with an unpleasant feeling in the feet, calves and thighs.

When iron deficiency anaemia is the cause, the problem can usually be treated with iron supplements.