March Week 2: Phenylketonuria/Metabolic Disorders


Peds in Review – Inborn Errors of Metabolism – 2009

Peds in Review – PKU – 1998

Peds in Review – Metabolic Disorders of the Newborn – 1994

State by state list of what is tested in newborn screen


Case 1
10 day old baby girl is brought in to clinic for her newborn visit. She was born at 39 weeks, to a G1P1 mother, with normal prenatal labs, APGARS of 8/9. She has been breast feeding well every 3 hours with 8-10 wet diapers per day. Mom has brought her in to discuss the results of her positive newborn screen for PKU.

1. Consider how you would discuss a positive PKU screen for this patient, and what confirmatory testing should be done?
2. What are the clinical manifestations of undetected PKU?
3. What is the treatment of PKU? And What is the long term prognosis?

Case 2

You are seeing a 2 week old in neurology clinic who has had tonic-clonic seizures essentially since birth which have been unresponsive to medical management. In addition mom reports that he has not been feeding well and frequently vomits after meals. On exam you find the infant to be severely hypotonic.

1. Which of the inborn errors of metabolism would you suspect?
2. What are the four symptoms which should increases suspicion for a metabolic disorder?
3. What lab tests are important to help rule in or out a metabolic disorder?
4. What is the appropriate medical management of a neonate suspected of having an inborn error of metabolism?
5. Are multivitamins beneficial in patients with errors of metabolism? And Why?

Cases/Questions by Dr. Kaitlin Balduf