Newborn Baby Screening Tests - Bloodspot test

How is the blood test done?

Mothers of all newborn babies are offered testing for certain conditions by testing a blood spot taken from the baby's heel. This is usually done by your midwife at home when your baby is 5 days old. A very small sample of blood is collected by pricking your baby's heel, using a special device and squeezing out a few drops of blood on to a card. Although this test may be uncomfortable, it is over very quickly. The sample is sent away for testing, and you will get the results by letter or phone in due course.

Which conditions might be tested for by the heel prick test?

Conditions which the heel prick test can screen for are as follows:

  • Sickle cell disease - this is an inherited blood disorder. Treatment started early in life, can prevent complications.
  • Cystic fibrosis - this is an inherited disorder that affects the internal organs, especially the lungs and digestive system. The heel prick test detects a chemical called immunoreactive trypsinogen. This is high in babies with cystic fibrosis. If it is high then a sweat test and genetic test are usually done to confirm the diagnosis. The earlier the diagnosis is made, the sooner treatment can begin which improves the outlook (prognosis).
  • Phenylketonuria - this is a very rare condition in which the body is unable to break down a substance called phenylalanine, which builds up in the blood and brain. It is really important for this to be picked up early. Early treatment significantly reduces the risk of brain problems and complications in the future.
  • Congenital hypothyroidism - this is a rare condition which can lead to impaired growth and mental development. However, treated babies can develop normally so it is important for it to be diagnosed early. If your baby was born prematurely (under 32 weeks) then your baby will need a repeat test when they are 28 days old.
  • Medium-chain acyl-Co-A dehydrogenase deficiency - this is a very rare, but potentially life-threatening, inherited disorder, where fat cannot be broken down by the body as well as usual. Babies with this condition develop normally, but recognising the condition early enables parents to make sure their babies and children with this condition eat regularly. When people with this condition go for a long period of time without eating there is a build-up of medium-chain fats inside the body, which can have a poisonous effect. Also, a sudden and severe drop in blood sugar levels can occur.
  • Since 2015, screening for four additional rare, but treatable, conditions has been introduced in England and Wales. These are:
    • Homocystinuria (HCU)
    • Maple syrup urine disease (MSUD)
    • Glutaric aciduria type 1 (GA1)
    • Isovaleric acidaemia (IVA)

Note: there is a slight variation of the tests performed throughout the UK. Your doctor, midwife or health visitor will be able to discuss these with you in more detail.

If you do not want your baby to have some or all of these conditions tested for in the heel prick test then you should inform your GP or midwife.

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Dr Mary Harding
Peer Reviewer:
Dr Louise Newson
Document ID:
28878 (v2)
Last Checked:
23 July 2017
Next Review:
22 July 2020

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. Patient Platform Limited has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.