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Sickle cell anaemia

Sickle cell anaemia, also known as sickle cell disorder, is an inherited blood condition where your red blood cells are crescent shaped and behave abnormally.

  • About sickle cell anaemia
  • Symptoms
  • Complications
  • Causes
  • Diagnosis
  • Treatment
  • Special considerations
  • Prevention of complications
  • Further information
  • Sources
  • Related topics

About sickle cell anaemia

In the UK, there are around 13,000 people who have sickle cell disease and 240,000 people who are carriers of the sickle cell gene (called the sickle cell trait). Most are of African or Caribbean descent.

Anaemia is a condition where you have too few red blood cells or not enough oxygen-carrying haemoglobin in your blood.

Inside your red blood cells is a protein called haemoglobin, which carries oxygen to the tissues around your body. If you have sickle cell disease, you have a type of haemoglobin called haemoglobin S (or HbS for short) instead of the normal haemoglobin A (HbA). HbS changes its structure when it gives up its oxygen to your tissues and the red blood cell becomes sickle (or crescent) shaped. Red blood cells containing haemoglobin S don't last as long as normal red blood cells, and this causes anaemia.

Red blood cells are normally soft round discs, shaped rather like a ring doughnut, which can easily flow through your blood vessels. However, red blood cells that have become sickle shaped tend to get stuck in small blood vessels, preventing other red blood cells from reaching tissues and organs where they are needed. This can cause damage to your organs and tissues and results in painful episodes known as sickle cell "crises".

Although sickle cell disease is present from birth, babies won't have a crisis until they are at least three to six months old. This is because another type of haemoglobin called fetal haemoglobin (HbF) protects the baby for the first few months after birth.

How often you have a crisis, what level of pain you suffer and how long each crisis lasts varies between individuals. Some crises can be treated with home treatments while others may require you to go to hospital. In between crises, you will usually feel quite well.


The following are common symptoms of sickle cell disease.

  • Excessive tiredness, breathlessness and paleness as a result of anaemia.
  • Pain - you can get pain as a result of a crisis in any part of your body but most commonly your chest, abdomen (tummy), back, jaw, legs and arms.
  • Swelling in your hands and feet - known as hand and foot syndrome - is another form of painful crisis. This is most common in young children between the ages of six and 18 months, and is rare after the age of four.

Although not necessarily a result of sickle cell disease, if you or your child have any of these symptoms you should visit your GP.

If you have a high fever or experience severe pain, particularly in the chest, spine or abdomen, you should seek urgent medical attention.


There are a range of complications that can occur as a result of sickle cell anaemia.

  • Severe infections - if you have sickle cell disease you may be more likely to catch severe infections such as pneumonia, septicaemia and meningitis (for more information, please see Related topics). It's important that you have appropriate immunisations.
  • Acute chest syndrome - about half of all people with sickle cell anaemia will get acute chest syndrome during their life. This affects your lungs; symptoms may include a temperature, cough and shortness of breath. If you have acute chest syndrome you will most probably have to go to hospital.
  • Stroke - this is caused by a blocked blood vessel in your brain (for more information, please see Related topics). Around one in 10 children with sickle cell disease suffer a stroke. Children can be screened to see if they are at risk of a stroke so that preventive actions can be taken.
  • Enlarged spleen - this occurs when red blood cells get trapped in your spleen, causing it to become enlarged and your haemoglobin level to decrease. You may need a blood transfusion (see Treatments) and your spleen may need to be removed.
  • Loss of vision - due to damage in the blood vessels at the back of your eye.
  • Organ damage - in particular damage to your lungs, kidneys and heart.
  • Delayed growth and puberty.
  • Painful and long-lasting erections in men (priapism) - around nine out of 10 men with sickle cell anaemia will have this at least once. In some cases it can lead to damage resulting in impotence (erectile dysfunction).
  • Stiff and painful joints.
  • Ulcers on the lower legs (mainly in adolescents and adults).
  • Needing to urinate frequently and having blood in your urine.


Sickle cell anaemia is an inherited condition, which means that the HbS gene is passed down from parent to child. If a child inherits two HbS genes - one from each parent - then he or she will have sickle cell disease.

If a child inherits an HbS gene from one parent but a normal haemoglobin (HbA) gene from the other parent, he or she will have sickle cell trait. If you have sickle cell trait, you won't suffer from the condition but you will have one HbS gene which you could pass on to your children.

There are other abnormal haemoglobins that can be inherited in the same way as HbS, and the combination of some of these with a single HbS gene can also lead to a sickling disease.

No one knows exactly what causes an episode of pain to happen, but there are a number of factors that are believed to play a role. These include:

  • infection
  • lack of oxygen - after exertion or exercise, or when at very high altitudes
  • being dehydrated (not drinking enough fluids)
  • getting too cold or too hot
  • major stress such as surgery or childbirth


If your doctor thinks you might have sickle cell disease or trait, he or she will take a blood sample from you which will be sent to a laboratory for testing.

In the UK, babies are tested for sickle cell disease soon after birth.

Amniocentesis or chorionic villus sampling (for more information, please see Related topics) are tests that can also be used to check whether your unborn baby has sickle cell disease while still in the womb (uterus).


With treatment, sickle cell disease can be effectively managed. The treatment you receive will depend on the type of crises you have and will vary between individuals. You will usually have a team of doctors to look after different aspects of your care.


You may need to have treatment for the pain. The treatment you are given depends on the amount of pain you are in. Over-the-counter painkillers, such as those you would normally take for a headache, may be enough. If it is severe your doctor may prescribe stronger medication, including opiates such as morphine, for which you may need to go to hospital.

Your doctor may prescribe antibiotics if you have an infection.

Other treatments

You will need to take in plenty of fluids. This may be by a drip into your vein if you are in hospital, or by increasing the amount of fluids you drink if you have had a minor crisis and are at home.

While you are in hospital, you may be given oxygen through a mask. If you aren't getting enough oxygen more of your red cells may become sickle shaped.

You may need to have a blood transfusion if you have serious complications such as acute chest syndrome, heart failure, or acute anaemia. Your doctor will inject blood or blood components into your bloodstream and so increase the amount of normal haemoglobin in your blood.

You may find that talking to a counsellor can help you learn to live with a sickle cell disorder.

Special considerations


If you are pregnant and have sickle cell disease, you will need regular monitoring from your doctor. You may be advised to drink plenty of fluids, take folic acid supplements and make sure you seek medical attention if you have an infection or crisis. Some women may require a blood transfusion during their pregnancy.

Starting a family

Your child may inherit sickle cell anaemia if you and your partner both have sickle cell disease or sickle cell trait. In these circumstances, if you are planning to have a child together it is recommended that you see your doctor or a genetic counsellor to discuss your options.

Prevention of complications

No one knows exactly what causes a crisis to occur. However, following these guidelines may help to prevent a crisis.

  • Maintain good general health and nutrition.
  • Keep warm and dry.
  • Drink plenty of fluids (or you may be given fluids by a drip if you go to hospital for treatment).
  • Take light to moderate exercise but avoid strenuous exercise.
  • Avoid environments or activities where there is low oxygen (for example high altitude activities such as skydiving or mountaineering).

Your doctor may prescribe:

  • a pneumococcal vaccine to protect you against the bacteria that cause pneumonia
  • antibiotics (usually penicillin) to prevent you from catching other bacterial infections
  • a medicine called hydroxyurea, which has been found to reduce the number of painful crises in people with sickle cell anaemia
  • antimalarial drugs to prevent you getting malaria
  • a folic acid supplement, especially if you are pregnant

Always read the patient information that comes with your medicine and if you have any questions, ask your doctor or pharmacist for advice.

Further information

The Sickle Cell Society 


  • The Sickle Cell Society. www.sicklecellsociety.org, accessed 9 August 2007
  • Sickle Cell Anaemia. World Health Organisation, 2006, A59/9. www.who.int
  • Meremikwu M. Sickle cell disease. BMJ Clinical Evidence. 2006; 15:1-3
  • Claster, S. Vachinsky E. Managing Sickle Cell disease. Student BMJ 2003; 11:450-453
  • Longmore M, Wilkinson I, Torok E. Oxford Handbook of Clinical Medicine. 5th edition. Oxford: Oxford University Press, 2001
  • Sickle cell anaemia. GP notebook.www.gpnotebook.co.uk, accessed 10 Aug 2007
  • Acute Chest Syndrome in Sickle cell disease: clinical presentation and course. Vichinsky, E. Blood, March 1997. Vol 89, No 5: pp 1787-1792
  • Boyd, J. Macklin, E. Strunk, R. et al. Asthma is associated with acute chest syndrome and pain in children with sickle cell anaemia. Blood. 2006
  • Sickle cell anemia. Medline Plus. www.nlm.nih.gov/medlineplus, accessed 10 Aug 2007
  • National screening committee policy - sickle cell disorders screening (in newborns). National Library for Health. www.library.nhs.uk, accessed 14 Aug 2007

Related topics

  • Anaemia - a general overview
  • Amniocentesis
  • Bone marrow or stem cell transplantation
  • Childhood immunisation
  • Malaria - prevention
  • Meningitis
  • Pneumonia
  • Stroke