Master's in Genetic Counseling (MGC)

Phenylketonuria Screening in Maryland

The state of Maryland has a two specimen screening protocol. The initial specimen is drawn after the baby has had 24 hours of protein containing feedings, and the subsequent specimen is usually drawn between one and four weeks of age.

Screening for PKU in the state of Maryland is performed by the Guthrie bacterial bioassay to determine the level of phenylalanine in the dried filter paper blood spot. A quantitative plasma amino acid profile is required for diagnostic testing.

The follow-up recommendations for PKU screens in the state of Maryland are as follows:

Newborn Screening Result	Interpretation	Follow-Up Action Recommended
phenylalanine <2 mg/dl	normal	none
phenylalanine 2-4 mg/dl, tyrosine <12 mg/dl	borderline	A follow-up filter paper specimen is required within 48 hours. If the follow-up specimen is abnormal, a quantitative plasma amino acid profile and genetic/metabolic consultation are required within 48 hours. Report any patient referred to a consultant to the Office for Hereditary Disorders at (410) 767-6730.
phenylalanine 4-6 mg/dl, tyrosine <12 mg/dl	probable hyperphenylalaninemia, may require dietary treatment	A follow-up filter paper specimen is required within 24 hours. If the follow-up specimen is abnormal, a quantitative amino acid profile and genetic/metabolic consultation are required within 48 hours. Report the patient to the Office for Hereditary Disorders at (410) 767-6730.
phenylalanine 6-20 mg/dl, tyrosine <12 mg/dl	probable hyperphenylalaninemia or classical PKU, will require dietary treatment	A quantitative amino acid profile and genetic/metabolic consultation are required within 24 hours. Report the patient to the Office for Hereditary Disorders at (410) 767-6730.
phenylalanine >20 mg/dl, tyrosine <12 mg/dl	probable classical PKU, will require dietary treatment	A quantitative amino acid profile and genetic/metabolic consultation are required within 24 hours. Report the patient to the Office for Hereditary Disorders at (410) 767-6730.
phenylalanine >2 mg/dl, tyrosine >12 mg/dl	possible disorder of tyrosine metabolism	A quantitative amino acid profile and genetic/metabolic consultation are required within 24 hours. Report the patient to the Office for Hereditary Disorders at (410) 767-6730.

NOTE: The adequacy of this test depends on the baby having had 24 hours of protein containing feedings.

 

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