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Iron Deficiency Anaemia: What Causes it and How to Test for it

Iron Deficiency Anaemia: What Causes it and How to Test for it

Iron deficiency anaemia is caused by not having enough iron in your blood, often as a result of blood loss or pregnancy. Common symptoms of low iron levels or anaemia include tiredness, lack of energy and pale skin. 

There are treatments available that can help raise your iron levels, but your GP will also want to investigate the underlying cause. An at-home blood test for iron, that works by measuring ferritin levels, will show whether you’re lacking in iron, and can be a great first step to getting help and feeling better.

7 minute read time

What causes iron deficiency?

Iron deficiency anaemia occurs when your body doesn’t have enough iron to produce haemoglobin. Haemoglobin is the protein in red blood cells that gives blood its red colour and enables the cells to carry oxygen throughout your body.

If you don’t get enough iron in your diet, or if you’re losing too much iron, your body cannot produce enough haemoglobin, and iron deficiency anaemia develops.

The causes of iron deficiency anaemia include:

Blood loss

Anything that causes you to lose blood could also mean your iron stores get too low and you become anaemic. The most common causes of blood loss are:


It’s common for pregnant women to develop iron deficiency anaemia. This is because the body’s stored iron has to provide for the growing baby as well as the mother’s own increased blood volume. During pregnancy, mother and baby need a lot more iron to make haemoglobin. The likelihood of iron deficiency is greater if you’re pregnant with more than one baby, or you were younger than 20 when you became pregnant.

Not eating enough iron-rich foods

Your blood can become low in iron if you don’t eat enough foods containing iron – such as meat, eggs and leafy greens. Babies and children need plenty of iron from their diets, too. Vegetarians and vegans may be at greater risk of iron deficiency anaemia if they don’t eat enough iron-rich alternatives to meat and dairy.

Not being able to absorb iron

Your small intestine absorbs iron from food in your bloodstream, so any health problem affecting your intestine may cause anaemia. Disorders of the gastrointestinal tract – such as Coeliac disease, Crohn’s disease and inflammatory bowel diseases (such as IBS) – affect your intestine’s ability to absorb iron (and other nutrients) from food. And if you’ve had surgery to remove or bypass part of your small intestine, that could affect your iron absorption, too.

What are the symptoms of iron deficiency?

Iron deficiency may not be noticeable at first, and there can be a very gradual onset of symptoms. Over time your body will show signs of a lack of iron, and some of the symptoms may disrupt your day-to-day life. The most common symptoms of low iron levels are:

There are other iron deficiency symptoms that are less common:


It’s important to seek treatment for iron deficiency anaemia, as there are some health problems that can develop if it’s left untreated:

How do you test for iron deficiency? 

A simple blood test for iron will identify iron deficiency. YorkTest offers a finger-prick test that you can do at home. Our Essential Health Check incudes a ferritin blood test which measures ferritin levels. As well as measuring ferritin levels the Essential Health Check also tests for important health markers covering cholesterol and triglycerides, liver function, vitamin D, B12, and folate deficiency.

The Essential Health Check looks for ferritin, which is a protein that stores iron in the body. Ferritin levels are a very useful indicator of iron deficiency as stores can be decreased before any blood iron levels are low. The test can also indicate if you have too much iron in your blood. 

Essential Health Check test

Your test results will make your level of ferritin very clear, with your ferrtin levels measured as μg/L. The results include recommended ferritin levels so you can compare your result to them. You’ll receive a supporting guidebook to help you make lifestyle changes in case you have low iron levels. If your test results indicate you have iron deficiency, you should see your GP. 

Iron deficiency anaemia isn’t something to try to diagnose and treat on your own. Your GP will want to investigate the underlying cause, as well as offer you treatment to bring your iron levels up safely.

Depending on your clinical history, your GP may refer you for the following:

It’s usually possible to discover the cause of anaemia, but sometimes it may be a problem other than iron deficiency. It could be due to inherited blood disorders called thalassaemia, which affect the production of haemoglobin. Or it could be sickle cell disease which affects the red blood cells.

People with infections or conditions such as chronic kidney disease, autoimmune diseases and inflammatory disorders may also have small red blood cells. If the cause of your anaemia is unclear, your GP may refer you to a haematologist (blood specialist).

Can you treat iron deficiency anaemia?

Once the reason for your iron deficiency has been found, your GP will recommend the best treatment for you. 

Depending on the cause, and your medical history, your treatment plan may mean:

If you have severe iron deficiency anaemia, you may need to take iron deficiency treatments intravenously or have red blood cell transfusions to help replace iron and haemoglobin quickly.

But the most likely treatment you can expect is a course of iron tablets, which also come in liquid form that children can easily take. 

Iron supplement tablets

Prescribed iron tablets are stronger than the iron supplements you can buy in pharmacies and supermarkets. You’ll typically need to take them for about six months or until you have normal iron levels. Your GP may suggest ways to help your body absorb iron from the tablets, such as:

Take iron tablets with vitamin C, which improves the absorption of iron. It can be a good idea to take your tablets with a glass of orange juice or a vitamin C supplement.

Some people get side effects when taking iron tablets, such as:

You can try taking the tablets with food (or shortly after eating) to reduce the risk of experiencing side effects. Please note that it’s crucial to keep taking the tablets, even if you experience some side effects.After you start taking iron tablets, your GP may request more blood tests over the next few months, to check that your iron is getting back to a healthy level.

Are there lifestyle changes that can help with iron deficiency anaemia?

As well as taking tablets to help with your iron deficiency anaemia, there are some changes you can make to your diet to increase your iron levels. Iron is a mineral that’s found in many foods that are already part of a varied and healthy diet.

Foods high in iron. liver, broccoli, persimmon, apples, nuts, legumes, spinach, pomegranate.

Iron-rich foods to eat

Try eating more of these iron-rich foods to up your iron intake:

Your body absorbs more iron from meat than from other sources. So if you don’t eat meat, you will need to eat more iron-rich, plant-based foods to get the same amount of iron intake. Try our recipe for puy lentil cottage pie, a nutritious, delicious meal made with iron-rich ingredients that you can easily adapt for a vegan diet.

You can also enhance your absorption of iron by drinking citrus juice or eating other foods rich in vitamin C at the same time as eating iron-rich foods. There’s vitamin C in broccoli and leafy greens as well as lots of fruits including grapefruit, strawberries and melons.0

Foods to avoid with iron deficiency

As well as boosting your intake of iron-rich foods, there are some things to limit as they can stop your body absorbing iron properly:

You don’t need to cut these out of your diet completely, but large amounts can affect your iron levels. 

There are ways to reduce the levels of phytic acids in some grains such as soaking, fermentation or sprouting. These methods mean you can still get the health benefits of plant-based foods without restricting your iron absorption.

More help and resources

You can find more guidance here:

*The Essential Health Check is only available in the UK, and for those aged 18 and over. The test is not suitable for pregnant women or those who are breastfeeding. Our blood tests and their results are for information only and are not a substitute for professional medical advice. The results cannot be used to diagnose, treat or cure medical or health conditions. If you’re concerned about your symptoms, please contact your GP or other medical professional.


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