Common Medical Tests and What They Mean

Blood Tests:

Haemoglobin Electrophoresis

This test is done to find out the type of haemoglobin a person has inherited from their parents: for example, sickle cell trait (Hb AS), haemoglobin C trait (Hb AC), sickle cell anaemia (Hb SS), sickle haemoglobin C disease (Hb SC) and sickle beta Thalassaemia (Hb SβThal.) This test will also show if there is any baby haemoglobin F (Hb F) present. Sometimes it is done to find out how many sickle red blood cells are present in the blood. This is called quantitative haemoglobin electrophoresis. If a person in having regular blood transfusions it helps the doctor work out how much blood transfusion the person needs.

Fetal Haemoglobin Test

Some people with sickle cell disease remain very well and have very few crisis and sickle related health problems. Some people have inherited a gene that makes their body continue producing high levels of baby haemoglobin F even in adulthood and they can have levels is as high as 25 - 30% (the usual amount is below 1% in people over one year of age). These individuals may have less painful episodes and crisis.

Full Blood Count (FBC)

This test examines the size, number and shape of the blood cells, how healthy they are and whether they are doing their job properly. Adults who do not have sickle cell disease or Thalassaemia disease usually have a haemoglobin level of between11 and 15. Children with sickle cell or Thalassaemia disease generally have lower levels and this depends on the type of condition they have inherited, for example, those with sickle haemoglobin C disease (Hb SC) and those with beta Thalassaemia Intermedia have slightly higher haemoglobin levels than those with sickle cell anaemia or beta Thalassaemia major.

This test also measures other parts of the blood: for example, the number of white cells, which help fight infection, and the number of platelets which help the blood to clot. The number of platelets may fall if the spleen gets very large.

Alpha Thalassaemia Trait Test

Normal adult haemoglobin A (Hb A) contains two beta chains and two alpha chains. Sometimes one or more of the genes controlling alpha chain production is absent and this results in alpha Thalassaemia trait. If a person has inherited alpha Thalassaemia trait as well as sickle cell anaemia it may in fact mean that the sickle cell anaemia will be less severe. This is because the concentration of haemoglobin in each red blood cell is less and therefore the red blood cell is less prone to sickling.

Reticulocyte Count

This test checks the number of young red blood cells present in the blood. It will show whether the bone marrow is working properly. The bone marrow is the factory where new red blood cells are made before they are released into the blood stream. Sometimes as a result of infection the bone marrow may stop making these. This will cause the haemoglobin level to fall and this can be fatal.

Blood Chemistry

A number of tests are done to check the level of various substances in the blood, substances which are vital for maintaining health, growth and development. For example, this test is done to check how well the kidneys and liver are working.

Glucose 6 Phosphate Dehydrogenase (G6PD) Deficiency Test

G6PD is an enzyme which protects the red blood cells against chemicals. Absence of the G6PD gene is found most commonly in people who come from the areas of the world where the sickle and Thalassaemia gene is found. If the enzyme is not present and certain foodstuffs or medicines are taken, the red blood cell may be destroyed, leading to a worsening anaemia. Some medications, including those commonly used in the treatment of fever, malaria, and pain can cause this problem, so it is important for this test to be carried out before giving pain and malaria medications. It is possible to inherit both the sickle cell gene and the G6PD deficiency gene.

Ferritin Levels or ZPP

This tests for the level of iron that is stored by the body, this is used to assess iron overload in patients having regular blood transfusions.

Urine Test:

Tests the urine may need to be checked if there is blood or protein in the urine, if there is a possibility of infection, or to look at how well the kidneys are working.

X-Rays and Scans:

Your child may need to have X-rays and scans taken for different reasons.

Chest X-Ray:

This is usually done to look for infection.

Bone X-Ray:

Sometimes done to monitor bone growth or to look for bone infection or the results of long term sickling (e.g. wearing away of hip bone).

Ultrasound Scan of the Abdomen:

To determine the size of the spleen and kidneys and to look for gallstones.

Echocardiogram:

Like an ultrasound scan but this looks at the size and functioning of the heart.

CT and MRI Scan:

This is a picture taken to look for tissue damage, For example, it may be used to help distinguish a painful crisis from Osteomyelitis (infection of the bone) or to look at the brain to see if there has been a silent stroke or the blood vessels in the brain are narrower than usual.

Doppler Blood Flow Studies:

Tests to see how well blood is flowing in any part of the body. Transcranial Doppler (TCD) in particular looks at how fast the blood is flowing through blood vessels in the brain. If the blood seems to be flowing very fast this may be due to narrowing of that blood vessel and may indicate that there is an increased risk of having a stroke.

Other scans or special tests may be requested, individuals should talk to their doctor or specialist nurse if any test is requested and they are not sure what the test is for.