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Newborn Screening Ontario
Screening Results

Carnitine Uptake Defect (CUD)Download version for offline viewing or printing

At a Glance

Approximate Incidence in Ontario

Unknown as so rare

Marker Measured


Screening can Prevent

Cardiomyopathy, hypotonia, hepatomegaly, encephalopathy, coma, death


Carnitine supplementation, avoid fasting

  • Screening is Important
    • In Ontario, a heel prick is used to take a few drops of blood from each baby shortly after birth. The blood is tested for more than 25 treatable diseases, including Carnitine Uptake Defect (CUD).
    • A screen positive result means that more tests are needed to know whether or not a baby has CUD. It does not mean that a baby has CUD. Babies identified at a young age through screening can be treated early to help prevent health problems.


  • What is CUD?

    CUD is a rare, inherited (genetic) disease.

    • Babies with CUD have trouble absorbing a protein called carnitine into their cells.
    • The cells need carnitine to make certain types of fat into energy.
    • Fats are an important source of energy for the muscles, brain, and heart, especially between meals.
  • Screening Positive for CUD
    • It is normal for parents and guardians to feel worried when their baby has a screen positive result. A ‘screen positive’ result does not mean that a baby has CUD. It means that there is a chance that the baby may have CUD.
    • Follow-up testing is important to find out whether the baby truly has CUD.
    • The baby’s health care provider or a health care provider at a newborn screening Regional Treatment Centre will discuss the results with the baby’s family.
    • Follow-up blood and urine tests will be arranged as soon as possible. Testing may also be done for the baby’s mother.
    • It can take a few days to weeks to find out if a baby truly has CUD or not. This waiting period can be hard for families.
  • Possible Follow-up Test Results
    • Normal – the baby does not have CUD.
    • Abnormal – the baby does have CUD and will need treatment. The family will be supported by a team of caring specialists.
    • Inconclusive – more testing is required. The baby will be followed closely by a specialist to ensure that he/she receives optimal care.
  • Signs and Symptoms

    Without treatment, symptoms can range from absent to severe.

    While most babies with CUD are normal at birth, early signs of the disease can include:

    • Poor growth
    • Excessive tiredness
    • Failure to feed properly
    • Sweating while feeding (due to heart failure)
    • Muscle weakness (may not happen in the newborn and early period)
    • Large liver

    Early treatment helps to prevent serious and life-threatening health problems such as:

    • Heart failure
    • Metabolic crisis -  a serious health condition caused by low blood sugar and/or the build-up of harmful substances in the blood. If a metabolic crisis is not treated, breathing problems, seizures, coma, brain damage and sometimes death can occur.

    Symptoms of a metabolic crisis are:

    • Poor feeding
    • Vomiting
    • Lethargy
    • Excessive sleepiness
    • Irritability

    Screening and treatment aim to prevent metabolic crises and help children with CUD lead healthy lives.

  • Treatment

    CUD is easily treated.

    Treatment involves:

    • Medication (large doses of carnitine)
    • Babies with CUD should not go for long periods of time without eating.
    • A diet low in certain fats is sometimes recommended.
    • Treatment begins as early as possible and is life long.
    • A team, including a metabolic doctor and a dietitian, cares for babies with CUD.
    • Babies with CUD have their health and development checked regularly.
    • Regular follow-up tests are used to monitor and adjust treatments.
  • Living with CUD

    With early detection and careful treatment, children with CUD are usually as healthy and intelligent as other children their age.