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Newborn Screening Ontario
Screening Results

Isovaleric Acidemia (IVA)Download version for offline viewing or printing

At a Glance

Approximate Incidence in Ontario

1 in 100,000 to 200,000

Marker Measured


Screening can Prevent

Encephalopathy, neurologic damage, coma, death


Avoid fasting, low protein diet, medication

  • 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 isovaleric acidemia (IVA).
    • A screen positive result means that more tests are needed to know whether or not a baby has IVA. It does not mean that a baby has IVA. Babies identified at a young age through screening can be treated early to help prevent health problems.
  • What is IVA?

    Isovaleric acidemia (IVA) is a very rare, inherited (genetic) disease.

    • Babies with IVA have trouble digesting an amino acid (building block of protein) called leucine.
    • Isovaleric acid is naturally produced when the body breaks down proteins (containing leucine) from the foods we eat, including breast milk and infant formula.
    • Babies with IVA cannot break isovaleric acid down into energy for the body.
  • Screening Positive for IVA
    • 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 IVA. It means that there is a chance that the baby may have IVA.
    • Follow up testing is important to find out whether the baby truly has IVA.
    • The baby’s health care provider or a health care provider at a newborn screening treatment centre will discuss the results with the baby’s family.
    • Follow up testing is arranged as soon as possible and involves blood and urine tests.
    • It can take a few days to weeks to find out if a baby truly has IVA or not. This waiting period can be hard for families.
  • Possible Follow-up Test Results
    • Normal – the baby does not have IVA.
    • Abnormal – the baby does have IVA 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

    Most babies with isovaleric acidemia are normal at birth but they are at risk of a serious health condition called a metabolic crisis.

    A metabolic crisis is a life-threatening episode caused by low blood sugar and/or the build-up of harmful substances in the blood. Symptoms of a metabolic crisis include:

    • poor feeding
    • vomiting
    • extreme fatigue
    • excessive sleepiness
    • irritability
    • muscle spasms

    If a metabolic crisis is not treated, breathing problems, seizures, coma, brain damage and sometimes death can occur. Screening and treatment aim to prevent metabolic crises and help children with IVA live healthier lives.

    Screening and early treatment also help to prevent the symptoms of IVA which include:

    • poor growth
    • low muscle tone
    • irritability
    • ‘sweaty feet-like’ odor
    • difficulty staying warm
    • immune system problems
    • negative effects of metabolic crises including learning problems and intellectual disability

    Depending on the type of IVA symptoms may appear in the first days after birth. Babies with mild IVA may have no symptoms at all, but they remain at risk for a metabolic crisis.

  • Treatment

    Treatment for IVA is started as early as possible and is usually life long.

    • Treatment may include:
      • frequent feeding, especially when ill (to prevent a metabolic crisis, babies with IVA must not go a long time without eating)
      • a low protein diet and special leucine-free medical foods
      • supplements and medications, such as glycine, carnitine and antibiotics may be prescribed
    • A team, including a metabolic doctor and a dietitian, cares for babies with IVA.
    • Babies with IVA have their health and development checked regularly.
    • Regular follow-up tests are used to monitor and adjust treatments.
    • If signs of a metabolic crisis (above) are present, urgent medical care must be found.
  • Living with IVA
    • Early treatment often allows babies with IVA to lead healthy lives with normal growth and intelligence.
    • A few children may develop some symptoms despite treatment.
    • As children get older, the risk of metabolic crises decreases.