Sickle Cell Disease

Most of our physical characteristics are inherited through the genes we take from our parents; for example, the shape of our nose, the colour of our skin and eyes, whether we are tall or short. We also inherit our haemoglobin (Hb) type from our parents, through the genes.

Haemoglobin (Hb) is the substance in the blood which gives it its red colour; it carries the oxygen (air) we breathe in through our nose to all our body parts; oxygen is vital for maintaining our life, see Normal Haemoglobin. Without red blood cells, the body cannot carry oxygen and without oxygen the body cannot live.

A small proportion of people inherit an unusual adult haemoglobin gene for example, Sickle Haemoglobin (Hb S), Haemoglobin C (Hb C), Beta Thalassaemia (Hb βThal) or any other unusual haemoglobin gene. There are over 1000 unusual haemoglobin known in humans, see Haemoglobin.

Sickle Cell Disease

Sickle Cell Disease (SCD) is a genetically inherited condition which affects the red blood cell haemoglobin.

If a person inherit two sickle haemoglobin, one from each parent, they will have a condition called Sickle Cell Anaemia (Hb SS). Where the sickle haemoglobin is inherited with another unusual haemoglobin, for example, Haemoglobin C the individual will have Sickle Haemoglobin C disease (Hb SC). If sickle is inherited with beta Thalassaemia, the individual will have Sickle Beta Thalassaemia, (Hb SβThal); for an illustration of how the inheritance works see Inheritance of Haemoglobin. These are just three types of the condition known collectively as Sickle ell Disease (SCD). Sickle cell anaemia is the most common and often the most severe of the three.

Red blood cells which contain mainly sickle haemoglobin and little or no normal haemoglobin lose their ability to keep the round, soft, spongy shape and texture of a normal red blood cell. The sickle haemoglobin inside the red blood cells stick together forming long stiff rods inside the red blood cell causing it to become hard, rigid, brittle and to assume the shape of a farmer’s sickle (banana shaped), as illustrated below.

Sickled Red Blood Cells

The red blood cells break easily, lose their ability to carry oxygen properly and depending on the type of sickle cell disease a person has and how well they are at any given time their red blood cells live for 5 - 20 days (instead of 120 days), this causes chronic anaemia, not because they are lacking in but because their red blood cells is not living long enough. People with sickle cell disease experience tiredness, feel lethargic, lose their appetite, are prone to getting infections, and will often become breathless during strenuous exercise. Sometimes, the red blood cells clog together and block the narrow blood vessels. This gives rise to pain (mild, moderate or excruciating); this painful episode is called a ‘sickle cell crisis’.

The sickle cell crisis pain can occur in any part of the body but occurs most commonly in joints.

During a crisis, a person may need to be admitted to hospital to find out what is causing the crisis and to give them care and treatment such as treating any infection and pain. Although these episodes are not constant, they are unpredictable in onset and severity.

Sickle Cell Disease Management

There is no simple cure for sickle cell disease but individuals can do a lot to prevent symptoms by learning as much as they can about the condition and taking steps to stay healthy. For example, avoiding damp, cold conditions, taking prescribed medications, drinking a lot of fluid, eating a healthy, balanced diet, avoid smoking, alcohol and stress / anxiety, and seeking prompt medical care when required especially at any sign of an infection. Because the anaemia is not caused by lack of iron it is important that iron tablets or iron tonics are NOT taken, unless it is prescribed by a doctor following proper investigation that proves that the person is definitely iron deficient.

The focus in medical management is treating the symptoms if and when they occur; treatments include giving adequate pain relief, provision of extra fluids, treatment of underlying infection or other causes of an acute painful episode, warmth and reassurance. Occasionally blood transfusion is required short or long term; some severely affected patients benefit from other therapies such as use of a medication called Hydroxyurea.

The only cure available is bone marrow transplantation but this is only suitable for a very few number of patients.

Fluid Intake

The recommended daily fluid intake which is in addition to fluid that is already in food is as follows:

Children:
Child’s weight Amount recommended
Less than 10 kilograms (kg) 150ml for every kg body weight in 24 hours
10−20kg 80ml for every kg body weight in 24 hours
20kg and above 40ml for every kg body weight in 24 hours
Example: If the child weighs 25kg: 25kg x 40ml = 1000ml
Adults:
Amount recommended
3 – 4 Litres in 24 hours

Medications, Immunisations and Vaccinations

Children and adults with sickle cell disease need to take some regular medications and some special vaccinations are recommended as follows:

Penicillin:
62.5mg twice a day until one year of age
125mg twice a day from one until five years of age
250mg twice a day from age five years into adulthood
 
Folic acid:
5mg once a day for children and adults

Childhood immunizations

Children should be given the same immunizations that other children get. These immunizations include diphtheria, whooping cough, tetanus (DPT), polio, Prevenar, haemophilus influenza (Hib), meningitis C, measles, mumps and rubella (MMR.)

Other immunizations include:

  • Pneumovax
  • Meningivac
  • Hepatitis B
  • Influenza (Flu)

Further information about these medications (‘Routine medication’, page 16) and vaccinations (‘Childhood immunizations’, page 17) is available in Routine medication - Care and Management of your child with sickle cell disease – A Parent’s Guide and for information on self care and management as well as other ways to manage sickle cell pain crisis see the Coping with Sickle Cell Disease & Pain – A Self-Help Manual for Children and Coping with Sickle Cell Disease & Pain – A Self-Help Manual for Adults manuals.

Difference between Sickle Cell Trait and Sickle Cell Disease

Sickle Cell trait (Hb AS) is not a disease or an illness it’s a healthy carrier state; because these individuals have one usual haemoglobin A and one unusual haemoglobin S, their red blood cells remain round and healthy they just carry the unusual sickle haemoglobin gene.

Sickle cell disease on the other hand can be a serious condition, even though it can affect individuals differently. While some people remain fairly well, others may experience many episodes of pain and discomfort which require hospitalization.

The Family Connection

A person can only get sickle cell trait, sickle cell disease or any other unusual haemoglobin from their parents through the genes they have inherited. These conditions cannot be transmitted like an infection. Each time a couple are expecting a child, the child will take one haemoglobin gene from each parent in order to have their own two haemoglobin genes. To find out how the inheritance works, see Inheritance of Haemoglobin.

Testing for Sickle Cell

It is important for people to get tested before planning a family so that they will know if there is any risk of their child inheriting sickle cell disease or any other unusual haemoglobin disease combination. Testing will enable a person to make an informed decision about marriage and having children. It is also important to know that a person has the sickle cell gene, even sickle cell trait, in case they need to have a general anaesthetic for an operation or dental treatment, see Common Medical Tests and What They Mean. To decide about testing it may be worth seeking the advice of a GP, nurse, doctor, midwife or by contacting the nearest National Sickle Cell / Thalassaemia Centre.