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Hyperphenylalaninemia Treatment & Management

  • Author: Georgianne L Arnold, MD; Chief Editor: Bruce Buehler, MD  more...
 
Updated: Nov 30, 2015
 

Medical Care

If available, patients should be evaluated at a phenylketonuria (PKU) treatment center. The extent of the hyperphenylalaninemia determines the nature and frequency of follow-up.[4]

In one study, 54% of patients with phenylalanine levels less than 600 mmol (10 mg/dL) demonstrated a decline of 30% or more in plasma phenylalanine levels when sapropterin (commercial tetrahydrobiopterin cofactor) was administered at a dose of 10 mg/kg/d.[5] The percentage of patients who responded declined with increasing plasma phenylalanine levels. Response to sapropterin may improve at a dose of 20 mg/kg/d.[6]

Preliminary studies are underway for injectable phenylalanine ammonium lyase, an enzyme substitute. This shows promise in animal studies as an alternative treatment to control phenylalanine levels.[7]

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Consultations

If dietary treatment is necessary, refer the patient to a dietitian experienced with PKU (usually a member of a PKU treatment team).

Refer families of affected infants to a medical geneticist or genetic counselor to review the inheritance of hyperphenylalaninemia.

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Diet

Determine the degree of dietary phenylalanine restriction for each patient based on untreated phenylalanine levels. For more detailed information on a phenylalanine-restricted diet, see Phenylketonuria.

Breastfeeding is usually possible and should not be stopped unless instructed by a local health official or treatment center.

Aspartame restriction may be indicated. Phenylalanine is a primary component of aspartame.

Aspartame may be present in many artificially sweetened substances, including medicines, vitamins, beverages, and foods. A pharmacist can help determine if a medication has a significant amount of aspartame.

The amount of aspartame in a children's vitamin or in a teaspoon of antibiotic may be significant for a child who can tolerate only 200 mg/d of phenylalanine, yet such a dose may be insignificant for a child who can tolerate more than 1000 mg/d.

Stringent phenylalanine-restricted diets have been reported to cause deficiencies of iron, zinc, selenium, and other nutrients and essential amino acids in patients with PKU. The diet requires careful monitoring by a professional trained in PKU management.

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Activity

Do not restrict activities.

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Contributor Information and Disclosures
Author

Georgianne L Arnold, MD Faculty, Department of Pediatrics, Divison of Genetics, University of Pittsburgh School of Medicine

Georgianne L Arnold, MD is a member of the following medical societies: American College of Medical Genetics and Genomics, Society for Inherited Metabolic Disorders, Society for the Study of Inborn Errors of Metabolism, American Society of Human Genetics

Disclosure: Received grant/research funds from Biomarin for clinical trial.

Specialty Editor Board

Mary L Windle, PharmD Adjunct Associate Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Nothing to disclose.

Margaret M McGovern, MD, PhD Professor and Chair of Pediatrics, Stony Brook University School of Medicine

Margaret M McGovern, MD, PhD is a member of the following medical societies: American Academy of Pediatrics, American Society of Human Genetics

Disclosure: Nothing to disclose.

Chief Editor

Bruce Buehler, MD Professor, Department of Pediatrics and Genetics, Director RSA, University of Nebraska Medical Center

Bruce Buehler, MD is a member of the following medical societies: American Academy for Cerebral Palsy and Developmental Medicine, American Academy of Pediatrics, American Association on Intellectual and Developmental Disabilities, American College of Medical Genetics and Genomics, American Association for Physician Leadership, American Medical Association, Nebraska Medical Association

Disclosure: Nothing to disclose.

Additional Contributors

Christian J Renner, MD Consulting Staff, Department of Pediatrics, University Hospital for Children and Adolescents, Erlangen, Germany

Disclosure: Nothing to disclose.

References
  1. Prick BW, Hop WC, Duvekot JJ. Maternal phenylketonuria and hyperphenylalaninemia in pregnancy: pregnancy complications and neonatal sequelae in untreated and treated pregnancies. Am J Clin Nutr. 2012 Feb. 95(2):374-82. [Medline].

  2. Mak CM, Ko CH, Lam CW, et al. Phenylketonuria in Hong Kong Chinese: a call for hyperphenylalaninemia newborn screening in the Special Administrative Region, China. Chin Med J (Engl). 2011 Aug. 124(16):2556-8. [Medline].

  3. Crujeiras V, Aldámiz-Echevarría L, Dalmau J, Vitoria I, Andrade F, Roca I, et al. Vitamin and mineral status in patients with hyperphenylalaninemia. Mol Genet Metab. 2015 Aug. 115 (4):145-50. [Medline].

  4. Ten Hoedt AE, Hollak CE, Boelen CC, et al. "MY PKU": increasing self-management in patients with phenylketonuria. A randomized controlled trial. Orphanet J Rare Dis. 2011 Jun 27. 6:48. [Medline]. [Full Text].

  5. Burton BK, Grange DK, Milanowski A, et al. The response of patients with phenylketonuria and elevated serum phenylalanine to treatment with oral sapropterin dihydrochloride (6R-tetrahydrobiopterin): a phase II, multicentre, open-label, screening study. J Inherit Metab Dis. 2007 Oct. 30(5):700-7. [Medline].

  6. Matalon R, Michals-Matalon K, Koch R, Grady J, Tyring S, Stevens RC. Response of patients with phenylketonuria in the US to tetrahydrobiopterin. Mol Genet Metab. 2005 Dec. 86 Suppl 1:S17-21. [Medline].

  7. Sarkissian CN, Gamez A, Wang L, et al. Preclinical evaluation of multiple species of PEGylated recombinant phenylalanine ammonia lyase for the treatment of phenylketonuria. Proc Natl Acad Sci U S A. 2008 Dec 30. 105(52):20894-9. [Medline]. [Full Text].

  8. Agostoni C, Verduci E, Massetto N, et al. Long term effects of long chain polyunsaturated fats in hyperphenylalaninemic children. Arch Dis Child. 2003 Jul. 88(7):582-3. [Medline]. [Full Text].

  9. Berlin CM, Levy HL, Hanley WB. Delayed increase in blood phenylalanine concentration in phenylketonuric children initially classified as mild hyperphenylalaninemia. Screening. 1995. 4:35-39.

  10. Diamond A, Prevor MB, Callender G, Druin DP. Prefrontal cortex cognitive deficits in children treated early and continuously for PKU. Monogr Soc Res Child Dev. 1997. 62(4):i-v, 1-208. [Medline].

  11. Fisch RO, Matalon R, Weisberg S, Michals K. Phenylketonuria: current dietary treatment practices in the United States and Canada. J Am Coll Nutr. 1997 Apr. 16(2):147-51. [Medline].

  12. Gassio R, Artuch R, Vilaseca MA, et al. Cognitive functions in classic phenylketonuria and mild hyperphenylalaninaemia: experience in a paediatric population. Dev Med Child Neurol. 2005 Jul. 47(7):443-8. [Medline].

  13. Recommendations on the dietary management of phenylketonuria. Report of Medical Research Council Working Party on Phenylketonuria. Arch Dis Child. 1993 Mar. 68(3):426-7. [Medline]. [Full Text].

  14. Scriver CR, Kaufman S, Eijsensmith RC. The hyperphenylalaninemias. The Metabolic and Molecular Bases of Inherited Disease. 1995. Vol 1: 1015-76.

  15. Procházková D, Jarkovský J, Haňková Z, Konečná P, Benáková H, Vinohradská H, et al. Long-term treatment for hyperphenylalaninemia and phenylketonuria: a risk for nutritional vitamin B12 deficiency?. J Pediatr Endocrinol Metab. 2015 Nov 1. 28 (11-12):1327-32. [Medline].

 
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Phenylalanine hydroxylase converts phenylalanine to tyrosine.
 
 
 
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