Continuous use of glycomacropeptide in the nutritional management of patients with phenylketonuria: a clinical perspective

Maria João Pena, Alex Pinto, Manuela Ferreira de Almeida, Catarina de Sousa Barbosa, Paula Cristina Ramos, Sara Rocha, Arlindo Guimas, Rosa Ribeiro, Esmeralda Martins, Anabela Bandeira, Cláudia Camila Dias, Anita MacDonald, Nuno Borges, Júlio César Rocha

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2 Citations (Scopus)


Background: In phenylketonuria (PKU), modified casein glycomacropeptide supplements (CGMP-AA) are used as an alternative to the traditional phenylalanine (Phe)-free L-amino acid supplements (L-AA). However, studies focusing on the long-term nutritional status of CGMP-AA are lacking. This retrospective study evaluated the long-term impact of CGMP-AA over a mean of 29 months in 11 patients with a mean age at CGMP-AA onset of 28 years (range 15–43) [8 females; 2 hyperphenylalaninaemia (HPA), 3 mild PKU, 3 classical PKU and 3 late-diagnosed]. Outcome measures included metabolic control, anthropometry, body composition and biochemical parameters. Results: CGMP-AA, providing 66% of protein equivalent intake from protein substitute, was associated with no significant change in blood Phe with CGMP-AA compared with baseline (562 ± 289 µmol/L vs 628 ± 317 µmol/L; p = 0.065). In contrast, blood tyrosine significantly increased on CGMP-AA (52.0 ± 19.2 μmol/L vs 61.4 ± 23.8 μmol/L; p = 0.027). Conclusions: Biochemical nutritional markers remained unchanged which is an encouraging finding in adults with PKU, many of whom are unable to maintain full adherence with nutritionally fortified protein substitutes. Longitudinal, prospective studies with larger sample sizes are necessary to fully understand the metabolic impact of using CGMP-AA in PKU.

Original languageEnglish
Article number84
JournalOrphanet Journal of Rare Diseases
Issue number1
Publication statusPublished - 13 Mar 2021


  • Amino acids
  • Casein glycomacropeptide
  • Nutritional status
  • Phenylalanine
  • Phenylketonuria
  • Tyrosine


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