Thalassaemia - Diagnosis 

Diagnosing thalassaemia 

Thalassaemia can be diagnosed using a blood test. Further DNA testing of the blood may be required so the exact type of thalassaemia can be determined.

Antenatal screening

The purpose of antenatal screening (screening that is carried out during pregnancy) is to check for inherited disorders such as sickle cell anaemia and to provide parents with information they need to make informed decisions.

Antenatal screening for the thalassaemia trait is available in areas where the condition is most common. These are typically cities and towns with large South Asian communities. In areas where thalassaemia is uncommon, a questionnaire on family origin is used as an initial screening tool to assess the risk of thalassaemia.

Pregnant women are routinely screened for the thalassaemia trait. If they test positive their partner will also be offered the test. If both parents have the thalassaemia trait, there is a 1 in 4 chance their baby will have thalassaemia.

Further testing is available (if you want it) to confirm whether your baby will definitely be born with thalassaemia. There are three methods of doing this:

  • chorionic villus sampling (CVS) - during CVS, a small sample of placenta (the organ that is attached to the womb lining during pregnancy) is removed from the womb and tested
  • amniocentesis - a small sample of the fluid inside the womb (amniotic fluid) is taken for testing
  • foetal blood sampling (FBS) -  under local anaesthetic, a small sample of blood is taken from your baby’s umbilical cord, or from the umbilical vein as it passes through their liver

Counselling

Being told  your baby will be born with thalassaemia can be traumatic and upsetting. You will be offered counselling to give you and your partner the opportunity to express your feelings and to ask questions about how the diagnosis may affect you.

The counsellor will inform you of different options available, allowing you to make a more informed decision about how to proceed with the pregnancy.

Pre-implantation genetic diagnosis (PGD)

Pre-implantation genetic diagnosis (PGD) is an option for couples who do not want to give birth to a child with thalassaemia but are unwilling to consider terminating a pregnancy.

PGD is similar to in-vitro fertilisation (IVF). IVF is a method of helping infertile couples conceive by surgically removing an egg from the woman's ovaries and fertilising it with the man’s sperm in a laboratory.

As with IVF, PGD involves removing eggs from a woman’s ovaries, which are fertilised using a sample of sperm taken from her partner. The fertilised embryo can be tested for thalassaemia. If the results are negative, the embryo can then be implanted into the woman’s womb.

PGD is a new procedure only available at a number of specialist thalassaemia centres. A list of sickle cell centres in England is available on the website of the Brent Sickle Cell and Thalassaemia Centre.

After birth

Unlike the related disorder sickle cell anaemia, newborn babies are not regularly screened for thalassaemia. There are two reasons:

  • blood tests are usually unreliable during the first six months of life
  • unlike sickle cell anaemia, thalassaemia does not present an immediate threat to a baby’s life (babies born with sickle cell anaemia have a high risk of catching serious infections and need immediate treatment with antibiotics)

If your baby does begin to develop symptoms as they grow older, the diagnosis can be confirmed using a blood test.

Assessing iron levels

People with beta thalassaemia major (BTM) will require regular blood transfusions, which will increase the level of iron in their body.

To remove the excess iron, they must have treatment called chelation therapy. This helps prevent serious complications from excess iron, such as heart or liver disease.

Read more information about how thalassaemia is treated.

Regular tests to measure iron levels are required to monitor the effectiveness of chelation therapy.

There are three main ways of assessing iron levels:

Blood tests

Blood tests provide a convenient way of measuring the amount of iron in your blood, although they do not provide a detailed assessment of how much iron may be collecting in certain organs, such as in your brain. The measurements provided by blood tests can also be distorted by other factors, such as infection.

Blood tests are used to provide a general overview of how well your chelation therapy is working, but cannot be used in isolation.

It is usually recommended that a person with thalassaemia receives a blood test at least every three months.

MRI scans

A magnetic resonance imaging (MRI) scan uses powerful magnetic waves to build up a detailed picture of the inside of your body. MRI scans are able to detect and then measure any iron in your organs.

The two organs known to be most vulnerable to the effects of iron are the liver and the heart.

It is usually recommended that you have an MRI scan of your liver at least once a year and an MRI scan of your heart at least once every two years. More frequent scans may be required if high levels of iron are found in your heart and liver.

Liver biopsy

A liver biopsy uses minor surgery to remove a tiny section of your liver to test it for the presence of iron.

An MRI scan is usually preferred to a liver biopsy as it is more convenient (for both the doctor and the person having the scan). However, if a detailed assessment of the level of iron in the body is required, a liver biopsy may be necessary.

Page last reviewed: 10/04/2012

Next review due: 10/04/2014

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