Blood spot test


A blood spot test is used to look for serious conditions that can’t be seen by just examining your baby. It’s usually carried out around 5 days after your baby’s born.

All newborn babies in Scotland will be offered a blood spot test. Your midwife will explain the test in detail, and ask for your permission to carry it out.

What will my baby’s blood be tested for?

The blood spot test screens for 9 inherited conditions:

  • sickle cell disease
  • cystic fibrosis (CF)
  • congenital hypothyroidism (CHT)
  • phenylketonuria (PKU)
  • medium-chain acyl-CoA dehydrogenase deficiency (MCADD)
  • maple syrup urine disease
  • isovaleric acidaemia (IVA)
  • glutaric aciduria type 1 (GA1 )
  • homocystinuria (HCU)

If you or your partner already has one of these conditions (or a family history of it), tell your health professional straight away.

Inherited conditions are usually passed from parents to children through altered genes.

What are altered genes?

Genes are what determine your characteristics, for example the colour of your hair to your blood group. For most of our characteristics, we inherit one gene from our mother and one from our father.

Babies only have the conditions if they inherit 2 altered genes – one from each parent. Babies who inherit just one altered gene are known as carriers. Carriers don’t have the inherited condition, but may pass the altered gene on to the next generation. If your baby is identified as a carrier, your health professional will give you more information. You can also talk to a genetic counsellor to discuss what this means for you, your baby and your family.

How the blood spot test is done

To do the test, your midwife pricks your baby’s heel to get a few drops of blood. The blood is then put onto a card and sent for testing.

The test may need to be repeated if:

  • there wasn’t enough blood on the card for testing
  • the card was damaged
  • one of the results was unclear

What if I decide not to have the test?

If you decide not to have your baby tested, you’ll be asked to sign a form.

This form:

  • confirms that the reasons for testing have been explained to you
  • states that you understand the possible effects of your baby not being screened

It’s only possible to test for all 6 inherited metabolic disorders at once, you cannot test for some disorders and not others.

Benefits and risks

As with any test, there are benefits and risks of having a blood spot test. It’s important you’re aware of these before you accept a screening invitation.


The benefits of having the blood spot test include:

  • one test screens for 9 conditions – all from just a few drops of blood taken from your baby’s heel
  • some tests can prevent disability and save your baby’s life
  • earlier treatment may improve health outcomes


There are no associated risks with having the blood spot test. However, by not having the test there’s a risk your baby could become seriously ill if these conditions aren’t identified and treated.

Sickle cell disease

Sickle cell disease is passed from parents to children through altered haemoglobin genes. Haemoglobin’s the part of the blood that carries oxygen around the body. The blood cells change to a ‘sickle’ (or hook) shape and get stuck in the small blood vessels. This can cause pain and damage to the baby or serious infection. In some cases, it causes death.

1 in every 2,500 babies born in the UK has the condition.

If your baby has sickle cell disease that isn’t detected, they would develop pain. They could suffer serious infection and damage to their body. This could be improved or even avoided with early screening and the right treatment.

Read more about sickle cell disease

Cystic fibrosis

Cystic fibrosis affects many parts of the body. For your baby, this means that the lungs and the pancreas are most affected. This leads to regular chest infections and problems digesting food and absorbing the nutrients they need.

1 in every 2,500 babies born in Scotland has the condition.

Cystic fibrosis occurs when a baby inherits an altered gene from each parent. You need to have both genes to have the condition. Both parents carry only one altered gene, so are unaffected. 1 in 25 people in Scotland is a cystic fibrosis carrier.

If your baby has cystic fibrosis that isn’t detected, there may be a delay in diagnosis. This means that your baby might develop problems that early treatment could help reduce or avoid.

Read more about cystic fibrosis

Congenital hypothyroidism

Babies with congenital hypothyroidism don’t produce enough of the hormone thyroxine. This is needed for healthy mental and physical development.

Congenital hypothyroidism is rare. It affects about 1 in every 3,500 babies born in Scotland.

A baby with untreated congenital hypothyroidism would grow at a slower rate than other babies. They might also have severe learning difficulties and may die.

Inherited metabolic disorders

Inherited metabolic disorders mean certain substances in food can’t be broken down in your baby’s body.

The blood sample will test for whether your baby has any of the following 6 inherited metabolic disorders:

  • phenylketonuria (PKU)
  • medium-chain acyl-CoA dehydrogenase deficiency (MCADD)
  • maple syrup urine disease
  • isovaleric acidaemia (IVA)
  • glutaric aciduria type 1 (GA1 )
  • homocystinuria (HCU)

These disorders all carry a very high risk of delayed development and irreversible learning disabilities. These can be severe if they’re not detected early.

Some of these disorders can also cause life-threatening illness, even coma under certain circumstances, and they can be associated with other medical problems. Without treatment, babies can become suddenly and seriously ill.

Breaking down fat

Babies with MCADD deficiencies may have issues breaking down fat to make energy under certain circumstances.

Build up of amino acids

Babies born with 5 of the 6 disorders find it harder to break down certain amino acids. Amino acids are fundamental parts of all foods except pure fat and sugar. When babies drink milk their body breaks the protein down into amino acids. Most of these are used to make new body proteins.

Any leftover amino acids have to be broken down further and used for energy or removed as waste. For babies with inherited metabolic disorders, some leftover amino acids can build up in their blood and other organs, such as their brain. This can cause serious issues.

Tests results

Most blood spot tests show no health conditions or issues. If this is the case, the results are sent to your health visitor who’ll discuss them with you at your next routine check.

If a possible health problem is found, you’ll be contacted.

Sickle cell disease

If your baby has sickle cell disease your health professional will arrange for you to see a haematologist (a doctor who specialises in blood conditions). They’ll organise more tests for your baby.

The blood spot test looks for sickle cell disease, but other blood disorders can be found.

How sickle cell disease is treated

Cystic fibrosis

If your baby has cystic fibrosis your health professional will arrange for you to see a cystic fibrosis specialist.

The specialist will:

  • confirm the diagnosis
  • make sure your baby gets the treatment needed
  • give you information, advice and support

If the test result isn’t clear, you might have another sample taken when your baby’s between 21 and 28 days old.

On rare occasions, cases of cystic fibrosis in babies will not be picked up by the screening test.

How cystic fibrosis is treated

Cystic fibrosis gene carriers

The blood spot tests also pick up the small number of babies who are healthy carriers of the gene. They’ll be unaffected by the condition, but carry it like their parents. They won’t need special treatment but may pass the gene to the next generation.

If your baby’s identified as a carrier, your health professional will give you more information and offer you an appointment with a Genetic Counsellor. The Counsellor will discuss what this means for you, your baby and your family.

Congenital hypothyroidism

If your baby has congenital hypothyroidism your health professional will arrange for you to see a specialist doctor for children. They’ll do some more tests.

Congenital hypothyroidism is easily corrected by giving your baby thyroxine as a medicine.

Inherited metabolic disorders

If an inherited metabolic disorder is found a member of the specialist inherited metabolic disorders team for children (a doctor, nurse or dietitian) will phone you and arrange to meet you and your baby that day.

The team will arrange further tests and start any necessary treatment straight away. They’ll be able to answer all of your questions.

Effective treatment is available to prevent the ill-effects of all 6 inherited metabolic disorders. This may include a carefully managed diet and/or medicines.

Treatment will need to continue for life, but it will allow your child to remain healthy and lead a full and active life.

What happens to the blood spot cards after testing is completed

Your baby’s leftover blood samples may be used for research, education and training. If this happens we’ll remove your baby’s personal details. If we ever need to use samples that are not anonymous, we’ll always ask for your consent first.

If you do not want the blood spot card to be used for research, please ask your midwife to write ‘no research’ in the comments box on the card.

What happens to your baby’s information after screening

Your baby’s personal health information will be kept private. This means it’s only shared with staff involved in their care.

Processes are reviewed regularly to make sure you’re offered the best service possible.

You have rights in relation to the access and the use of your baby’s personal health information.

Learn more about privacy and confidentiality when using the NHS

Read more about data protection and the NHS

Further information

If you’re unsure about anything, or have any questions about the blood spot tests, phone:

Information in other languages and formats

Information leaflets from Public Health Scotland are available in

  • British Sign Language (BSL), Audio, Easy Read, and Large Print formats
  • English and other languages

You can request another format or language (for example Braille) by emailing

Easy Read (English)
Simplified Chinese (Mandarin)

Last updated:
25 June 2024