NBS - Phenylketouria (PKU)

The newborn metabolic screening PKU test is a heel‑prick bloodspot test done 24–72 hours after birth to detect phenylketonuria (PKU) and related metabolic disorders. It measures blood phenylalanine levels; high levels suggest PKU. Early diagnosis allows prompt dietary treatment (low‑phenylalanine diet) to prevent intellectual disability and developmental problems. Positive screens require confirmatory testing and specialist follow‑up.

Five symptoms of phenylketonuria (PKU) are: intellectual disability/developmental delay; seizures; behavioral problems (irritability, hyperactivity); a characteristic musty (mousy) body or urine odor; and hypopigmentation (fair skin, light hair). If untreated, PKU can cause permanent brain damage; newborn screening and a lifelong low‑phenylalanine diet greatly reduce risk. Early treatment prevents most complications.

No. PKU (phenylketonuria) is an inherited metabolic disorder causing buildup of phenylalanine that can damage the brain if untreated. It is not a form of autism, though untreated PKU may cause developmental delay, learning and behavioral problems that can resemble autistic traits. With newborn screening and dietary management, most people with PKU avoid these neurological effects.

If a PKU screening is positive, the baby is referred urgently to a metabolic specialist for confirmatory blood tests and genetic testing. Treatment—typically a low‑phenylalanine diet with specialized formula and tyrosine supplementation—starts quickly to prevent brain damage. Ongoing blood monitoring, dietary adjustments, multidisciplinary care, and genetic counseling follow; some cases require additional therapies and lifelong follow‑up.

Seven conditions (criteria) for implementing a newborn screening test: 1) The condition is an important health problem; 2) Its natural history is well understood; 3) There’s a detectable pre‑symptomatic or latent stage; 4) There’s a reliable, valid, acceptable screening test; 5) An effective treatment is available; 6) Facilities exist for diagnosis and treatment; 7) Screening is cost‑effective with an agreed policy on whom to treat.

Newborn screening for phenylketonuria (PKU) is routinely offered and required in many countries as part of standard newborn screening programs. Policies vary: some jurisdictions legally mandate the heel‑prick blood spot test, while others allow parental refusal. Early testing (typically 24–72 hours after birth) enables prompt dietary treatment to prevent intellectual disability and other complications.