Phenylketonuria (PKU) Test

PKU (Phenylketonuria) Screening

Why It Is Done

A phenylketonuria (PKU) test is done to see whether a newborn baby has the enzyme to use phenylalanine in his or her body.

It is important to test your baby for PKU soon after birth to prevent brain damage. Phenylalanine blood levels in a baby with PKU start to rise within 24 hours of drinking breast milk or formula. A PKU test done 2 to 3 days after birth will show whether your baby has PKU. State laws say that newborn PKU tests must be done within a few days after birth.

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Author:	Debby Golonka, MPH	Last Updated: February 27, 2008
Medical Review:	Michael J. Sexton, MD - Pediatrics Thomas Emmett Francoeur, MDCM, CSPQ, FRCPC - Pediatrics
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