Phenylketonuria (PKU) Test

PKU (Phenylketonuria) Screening

What Affects the Test

Reasons your baby may not be able to have the test or why the results may not be helpful include:

• Your baby was born early (premature). A baby who weighs less than 5 lb (2.3 kg) may have high levels of phenylalanine but not have phenylketonuria (PKU).
• Your baby has been drinking milk for less than 24 hours. Best results occur after your baby has been breast-feeding or drinking formula for 2 full days.
• A baby is vomiting or refusing to eat. If the PKU test is done before your baby has eaten for 2 days, the results may not be correct.
• Your baby is getting antibiotics.

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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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