PKU screening is a recommended newborn screening in which a clinician checks to see if a baby has phenylketonuria (PKU), a rare metabolic disorder. This test is routinely performed after birth in many regions of the world, often within the first 24 hours of the baby's life. It is one among a group of newborn screenings which are intended to identify issues early so that they can be addressed before they cause complications. These screenings are offered to new parents by pediatricians and neonatologists who can also discuss additional optional screenings which may be recommended for specific situations.
People with phenylketonuria are unable to process phenylalanine, an important amino acid. Phenylalanine builds up in the body as a result, leading to the development of neurological problems including seizures and brain damage. Damage can occur in only a few weeks, making it critical to identify phenylketonuria with a PKU screening as early as possible so that steps can be taken to address it.
Classically, the PKU screening is done with a heel stick. The baby's heel is wiped with alcohol and pricked to collect a small blood sample which can be run to check for phenylketonuria. Sometimes the test is conducted with urine. If the results are negative, the baby is given a clean bill of health, and if they are positive, the baby is referred to a metabolic specialist. The doctor can make recommendations about management of PKU to reduce the risk that the baby will develop neurological problems.
PKU is genetic, and the incidence varies among different populations. People who have a family history of PKU should be sure to mention this before a PKU screening, and people should also make sure that their clinicians are familiar with their family history in general. This can be used to identify risk factors which may be considered when recommending newborn screenings.
If a baby is not checked for PKU with a PKU screening and the baby has the condition, symptoms will occur within a few weeks. They can include a musty odor, a rash, and restlessness. If parents notice a change in their infant, whether or not the infant has been screened for common disorders, they should contact a pediatrician for an evaluation. A wide range of things can lead to things like personality changes, rashes, alterations in sleeping patterns, and other issues in a newborn, and clinicians are usually happy to conduct an exam to be on the safe side.
