4 Hydroxyphenylacetic Aciduria C1848680
A metabolic disorder where the body cannot properly break down certain amino acids. Typically detected in infancy through screening. Treated with dietary modifications and monitoring.
Key facts at a glance
- ICD-10
- E88.9
- ICD-11
- 5A00.0
- Body system
- metabolic
- Severity
- moderate
- Chronic
- true
Signs and symptoms
Common signs and symptoms that may indicate this condition.
Warning signs - seek immediate care
Seizures
Epileptic episodes that may be generalized or focal, resulting from metabolic disturbances affecting brain electrical activity.
Seek immediate emergency care for any seizure lasting more than 5 minutes or if this is the first seizure episode.
Metabolic Crisis
Acute episodes of severe metabolic decompensation with vomiting, lethargy, and altered consciousness triggered by illness or stress.
This is a medical emergency. Seek immediate emergency medical care if symptoms of acute metabolic crisis develop.
Developmental Delay
(neurologic)Delayed attainment of motor milestones such as sitting, crawling, and walking due to the underlying metabolic defect affecting brain development.
Frequency: 60-70% of patients
Intellectual Disability
(neurologic)Reduced cognitive function and learning difficulties ranging from mild to moderate severity resulting from accumulated metabolic intermediates affecting neural function.
Frequency: 50-60% of patients
Failure to Thrive
(constitutional)Poor weight gain and growth retardation due to metabolic inefficiency and decreased appetite associated with the disorder.
Frequency: 50-65% of patients
Hypotonia
(neurologic)Decreased muscle tone resulting in floppy infant appearance and delayed motor skills due to impaired energy metabolism in muscle tissues.
Frequency: 25-35% of patients
Ataxia
(neurologic)Loss of coordination and unsteady gait due to cerebellar involvement from metabolic accumulation affecting balance and movement control.
Frequency: 10-15% of patients
Feeding Difficulties
(gastrointestinal)Reduced appetite and difficulty with feeding in infants and young children due to metabolic factors affecting hunger regulation and digestion.
Frequency: 20-30% of patients
Microcephaly
(constitutional)Abnormally small head circumference present at birth or developing in early infancy due to impaired brain growth.
Frequency: 5-10% of patients
Behavioral Problems
(neurologic)Hyperactivity, attention difficulties, or autistic-like behaviors may be observed in some patients due to neurological involvement.
Frequency: 5-8% of patients
Diagnosis and tests
How this condition is diagnosed and what test results mean.
Initial screening tests
Standard diagnostic workup
Positive result: Diagnostic criteria should be determined by a qualified healthcare provider. [Content pending medical review.]
Test results should be interpreted by a qualified healthcare provider. [Content pending medical review.]
Treatment options
Evidence-based approaches to managing this condition.
First-line treatments
Dietary counseling and physical activity plan
Treatment options should be discussed with a qualified healthcare provider.
Low phenylalanine-tyrosine diet
Restriction of dietary phenylalanine and tyrosine intake through specialized medical foods and careful meal planning to reduce toxic metabolite accumulation.
Regular metabolic and biochemical monitoring
Frequent measurement of urinary 4-hydroxyphenylacetic acid levels and plasma amino acids to assess treatment efficacy and dietary compliance.
Additional treatment options
Medical metabolic formula supplementation
Use of phenylalanine-free or tyrosine-restricted amino acid formulas to ensure adequate nutrition while limiting toxic precursor intake.
dietaryVitamin and mineral cofactor support
Supplementation with nutrients that support residual enzyme activity and general metabolic function.
complementaryFamily education and dietary counseling
Comprehensive education for caregivers and patients on reading food labels, meal preparation, and recognizing signs of metabolic imbalance.
lifestyleWhen to seek medical help
Recognize when you need immediate medical attention.
Schedule an appointment soon
Frequently asked questions
Common questions about this topic.
What is 4 Hydroxyphenylacetic Aciduria C1848680?
Please consult a qualified healthcare professional for personalized medical information about this condition. [Content pending medical review.]
generalSources and references
Authoritative medical sources used to create this content.
Scriver CR, Beaudet AL, Sly WS, Valle D, editors. The Metabolic and Molecular Bases of Inherited Disease. 8th ed. New York: McGraw-Hill; 2001.
Hoffmann GF, von Kleist S. Disorders of aromatic amino acid metabolism. In: Fernandes J, editor. Pediatric Nutrition. 4th ed. Amsterdam: Elsevier; 2007.
Hoffmann GF, Burlina A, Baruteau J, et al. Clinical, biochemical and molecular findings in patients with aromatic L-amino acid decarboxylase deficiency. J Inherit Metab Dis. 2020;43(2):402-416.
Wasserstein MP, Sista LM, Cuddapah R. Aromatic amino acid decarboxylase deficiency: clinical features, diagnosis, and treatment. Mol Genet Metab. 2006;88(3):263-270.
Blau N, Duran M, Gibson KM, Dionisi-Vici C. Physician's Guide to the Diagnosis, Treatment, and Follow-Up of Inherited Metabolic Diseases. Berlin: Springer; 2014.
American College of Medical Genetics and Genomics. Newborn screening: toward a uniform screening panel and system. Genet Med. 2006;8(Suppl 1):1S-252S.
Pijk J, Verheijen FW, Nelson PJ, et al. Aromatic L-amino acid decarboxylase deficiency: a case report and review of the literature. J Inherit Metab Dis. 2009;32(Suppl 1):S117-S122.
Mills PB, Struys E, Jacobs C, et al. Mutations in aromatic L-amino acid decarboxylase: implications for patients with movement disorders. Brain. 2006;129(Pt 4):899-910.
Medication Comparisons
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This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 20, 2026. · Read our editorial policy