Summary
Definition
History and exam
Key diagnostic factors
- family history of PKU
- positive newborn screen for PKU
Other diagnostic factors
- intellectual disability
- microcephaly
- eczema
- light pigmentation of eyes and hair
- seizures
- mousy odor of urine
Risk factors
- family history of PKU
- white ancestry
Diagnostic investigations
1st investigations to order
- newborn screening for metabolic disorders
Investigations to consider
- quantitative plasma amino acid analysis
- blood dihydropteridine reductase (DHPR) assay
- urine neopterin to biopterin ratio
- mutation analysis of phenylalanine hydroxylase gene
- tetrahydrobiopterin (BH4)-responsiveness test
Treatment algorithm
all patients
Contributors
Authors
Barbara K. Burton, MD
Professor of Pediatrics
Northwestern University Feinberg School of Medicine
Director
PKU Clinic
Ann and Robert H. Lurie Children’s Hospital of Chicago
Chicago
IL
Disclosures
BKB has received consulting fees and funding for the conduct of clinical trials from BioMarin Pharmaceutical, the manufacturer of sapropterin and pegvaliase (pegylated phenylalanine ammonia-lyase).
Peer reviewers
Harvey L. Levy, MD
Senior Physician in Medicine/Genetics
Children's Hospital Boston
Professor of Pediatrics
Harvard Medical School
Boston
MA
Disclosures
HLL has served on the PKU Scientific Advisory Board for BioMarin Pharmaceuticals Inc. and has received consultation fees from the company for attending meetings, giving lectures, and participating in symposia. BioMarin markets treatment for phenylketonuria.
Berthold Koletzko, MD
Professor of Pediatrics
University of Munich
Head of Division of Metabolic Diseases and Nutritional Medicine
Dr von Hauner Children's Hospital
Ludwig-Maximilians-University of Munich
Lindwurmstr
Germany
Disclosures
BK has received research support from Danone Medical Nutrition and is the recipient of a Freedom to Discover Award of the Bristol Myers Squibb Foundation.
Differentials
- Inborn errors of tetrahydrobiopterin (BH4) synthesis
- Hepatic dysfunction
- Extreme prematurity
More DifferentialsGuidelines
- The complete European guidelines on phenylketonuria: diagnosis and treatment
- Phenylalanine hydroxylase deficiency: diagnosis and management guideline
More GuidelinesPatient leaflets
ADHD: what is it?
ADHD: questions to ask your doctor
More Patient leafletsLog in or subscribe to access all of BMJ Best Practice
Use of this content is subject to our disclaimer