Anaemia is when the number of red blood cells (RBCs) in your blood is below the normal level or you have less haemoglobin than normal in each red blood cell. Iron deficiency anaemia is the most common type of anaemia, but there a number of different types, each of which has a different cause.

When you have anaemia, your blood doesn’t have enough haemoglobin to meet your body’s oxygen needs. The most common symptoms of anaemia are tiredness, a pale complexion and shortness of breath. The severity of your symptoms will depend on the exact cause of your anaemia and the type of anaemia you are suffering from. Your symptoms may be noticeable immediately, or gradually if the anaemia is caused by a long-term problem.

Iron deficiency anaemia
Iron deficiency anaemia is the most common type of anaemia. This occurs when your body lacks the iron it needs to produce haemoglobin. Without haemoglobin, your red blood cells can’t perform the important task of moving oxygen around your body. Iron deficiency anaemia can occur if you lose a lot of blood, if your diet doesn’t provide enough iron, or if you’re pregnant.

Vitamin B12 deficiency anaemia

Your body needs vitamin B12 for a number of key tasks, including making red blood cells. A lack of vitamin B12 reduces the number of red blood cells your body produces, and the ones it does make are not as effective. A lack of vitamin B12 may be caused by your diet or if your body isn’t able to absorb the vitamin normally.

Folate deficiency anaemia

Your body uses folate to make cells; with insufficient folate, your body won’t make enough red blood cells for its needs. Folate deficiency anaemia may be caused by certain medication, or by your diet (insufficient green vegetable for example) or by overcooking these foods. This condition is also more common when you’re pregnant because your body uses more folate than normal; folate supplement can be given to overcome this.

Anaemia of chronic diseases (ACD)

Some chronic conditions, for example rheumatoid arthritis, or a traumatic injury or major surgery, can cause ACD. The inflammation that results from these conditions can interfere with iron absorption by your body, meaning that fewer red blood cells are produced.

Anaemia of chronic kidney disease

Kidney disease or damage can cause anaemia, because your kidneys produce less of a hormone called erythropoietin which is the hormone that stimulates your body to make more red blood cells.

Haemolytic anaemia

Haemolytic anaemia occurs when your red blood cells are prematurely destroyed and removed from your blood, usually because your own body is producing an antibody that breaks down your own red blood cells. This may be an inherited condition, or it can be acquired.

Aplastic anaemia

Aplastic anaemia is a rare condition that affects the bone marrow where red blood cells are made. The symptoms of aplastic anaemia vary but in its most aggressive form  it can be a life-threatening condition. Certain types of drugs, exposure to radiation and a number of medical conditions can cause aplastic anaemia; however, in most cases, the exact cause is unknown (idiopathic).

Sickle cell anaemia

Sickle cell anaemia is an inherited condition that means your body produces faulty haemoglobin and the red blood cells appear in an unusual crescent (sickle) shape.  Under certain circumstances these cells block small blood vessels, interfering with blood flow around the body and causing severe pain (this is known as a vaso-occlusive crisis or a sickle cell crisis).

Anaemia is caused because there are not enough red blood cells (or haemoglobin) to meet your body’s need for oxygen. In general terms, this can happen when; your body lacks the vital vitamins and minerals it needs to make haemoglobin; your body destroys or loses the red blood cells it needs (when you bleed for example); or when your body makes ineffective red blood cells.

There are a number of different types of anaemia, each with different causes (see Condition Overview above). The most common form of anaemia is iron deficiency anaemia, where the body doesn't have enough iron, which decreases the production of red blood cells.

The most common causes of iron deficiency anaemia are:

  • Monthly periods - heavy bleeding over several menstrual periods is one the commonest causes of iron deficiency anaemia; it’s called menorrhagia.
  • Pregnancy - iron deficiency during pregnancy is very common because your iron is used to ensure your baby grows healthily. Iron supplements may be needed, or an increase in the amount of iron in the diet.
  • Gastrointestinal blood loss - bleeding in the gastrointestinal tract (stomach and intestines) is a common cause of iron deficiency. Most people don't notice blood in their stools or any changes in their bowel habits. The bleeding may be caused by; non-steroidal anti-inflammatory drugs (such as ibuprofen or aspirin); stomach ulcers; angiodysplasia; or, rarely, gastrointestinal (stomach or bowel) cancer.
  • Chronic kidney disease (CKD) - can lead to iron deficiency anaemia, which is normally treated with iron supplements.
  • Malabsorption - where your body can't absorb enough iron from your food, perhaps because you have coeliac disease, or have had surgery to remove your stomach (gastrectomy) or part of it.
  • Insufficient iron in your diet -it's rare for iron deficiency anaemia to be caused solely by a lack of iron in your diet, unless you're pregnant

Other causes of blood loss that can lead to iron deficiency anaemia include:

  • inflammatory bowel disease
  • oesophagitis
  • schistosomiasis
  • blood donation
  • trauma
  • regular nosebleeds
  • haematuria (blood in your urine)


The symptoms of anaemia may be so mild you don’t realise there’s anything wrong. If you do experience symptoms, they will different depending on the type of anaemia you have. However, common symptoms of anaemia include:

  • feeling tired/lethargic
  • being weak
  • experiencing dizziness
  • being short of breath
  • having heart palpitations (unusual or very noticeable heartbeats)
  • dry or brittle nails

Your doctor should be able to diagnose anaemia after a short examination and by discussing your symptoms and medical history. A blood test will be required to confirm the diagnosis and identify the exact cause.

You may have a full blood count (FBC) to check the levels of haemoglobin in your blood and the total numbers of red cells. Your iron, vitamin B12, and folate levels can also be checked, and a blood film test will look at the size and shape of your red blood cells.

Blood tests

Blood tests are a commonly used diagnostic tool to assess your general state of health, or to check for something more specific.

What next?

If you are suffering with a suspected condition, you should seek the advice of your doctor who will be able to refer you to Benenden Hospital for diagnosis and treatment.

There are four ways to access treatment at Benenden Hospital which include self-funding, using private medical insurance or your Benenden membership, or through the NHS e-Referral scheme.