Iron deficiency anaemia occurs when the body does not have enough iron. A lack of iron can be caused by a number of factors.
Some are outlined below.
In women of reproductive age, periods are the most common cause of iron deficiency anaemia.
Usually, only women with particularly heavy periods develop iron deficiency anaemia. If you have heavy bleeding over several consecutive menstrual cycles, it is known as menorrhagia.
It is very common for women to develop iron deficiency during pregnancy. This is because your body needs extra iron so your baby has a sufficient blood supply and receives necessary oxygen and nutrients. Many pregnant women require an iron supplement, particularly from the 20th week of pregnancy.
Gastrointestinal blood loss
Your gastrointestinal tract is the part of your body responsible for digesting food. It is made up of the:
- stomach - a sac-like organ that helps digest food by churning it and mixing it with acids to break it down into smaller pieces
- intestines - which digest and absorb food and liquid
Bleeding in the stomach and intestines is the most common cause of iron deficiency anaemia in men and in women who have been through the menopause (when a woman’s monthly periods stop).
Some of the causes of gastrointestinal bleeding are outlined below.
Non-steroidal anti-inflammatory drugs (NSAIDs)
Non-steroidal anti-inflammatory drugs (NSAIDs) can cause bleeding in the stomach. Ibuprofen and aspirin are two commonly prescribed NSAIDs.
If your GP suspects your medication is causing gastrointestinal bleeding, they may be able to prescribe a less harmful medicine as an alternative. Do not stop taking a medicine prescribed for you unless your GP advises you to.
The acid in your stomach (which usually helps your body to digest food) can sometimes eat into your stomach lining. When this happens, the acid forms an ulcer (an open sore). This is also known as a peptic ulcer.
Stomach ulcers can cause your stomach lining to bleed and this blood loss can lead to anaemia. In some cases the blood loss can cause you to vomit blood or pass blood in your stools (faeces). However, if the ulcer is slow bleeding, you may not have any symptoms.
In some rare cases, gastrointestinal bleeding can be caused by cancer, usually of the stomach or colon (part of the bowel, which makes up the digestive system). According to Cancer Research UK, around 7,500 cases of stomach cancer are diagnosed in the UK every year. This makes up around 2% of all cancers.
In diagnosing the cause of your anaemia, your GP will check for possible signs of cancer. If your GP suspects cancer, you will be immediately referred to a gastroenterologist (a specialist in treating conditions of the digestive system) for a more thorough examination. This way, if cancer is found, it can be treated as quickly as possible.
Read more information about stomach cancer and bowel cancer.
Gastrointestinal bleeding can also be caused by a condition called angiodysplasia. This is an abnormality of blood vessels in the gastrointestinal tract that can cause bleeding.
Chronic kidney disease
Many people with chronic kidney disease (CKD) develop iron deficiency anaemia.
Most people with kidney disease will be given iron supplements through an injection administered intravenously (into a vein). However, daily ferrous sulphate tablets may be tried first.
Read more information in the NICE guidelines on treating anaemia in people with chronic kidney disease.
Other conditions or situations that cause blood loss and may lead to iron deficiency anaemia include:
- inflammatory bowel disease - a condition that causes inflammation (redness and swelling) in the digestive system, such as Crohn’s disease and ulcerative colitis
- oesophagitis - inflammation of the gullet (oesophagus) caused by stomach acid leaking through it
- schistosomiasis - an infection caused by parasites and mainly found in sub-Saharan Africa
- blood donation: donating a large amount of blood may lead to anaemia
- trauma - a serious accident, such as a car accident, may cause you to lose a lot of blood
- nosebleeds - if you have a lot of nosebleeds, this may lead to anaemia, although it is rare
- haematuria (blood in your urine) - also rare and may be the symptom of another condition
Malabsorption (when your body cannot absorb iron from food) is another possible cause of iron deficiency anaemia. This may occur if you have:
- coeliac disease, a condition that damages the lining of the intestines
- a gastrectomy, a medical procedure to surgically remove your stomach, for example to treat stomach cancer
Unless you are pregnant, it is rare for iron deficiency anaemia to be caused solely by a lack of iron in your diet.
Some studies suggest vegetarians or vegans are more at risk of iron-deficiency anaemia due to the lack of meat in their diet. However, it is possible to gain enough iron in a vegetarian or vegan diet through other types of food such as:
- 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
Read more information about vegetarian and vegan diets.
Pregnant women may have to increase the amount of iron-rich food they consume during their pregnancy to help avoid iron deficiency anaemia.
Read more information about good sources of iron.