The management of phenylketonuria in adult patients in Italy: a survey of six specialist metabolic centers

Curr Med Res Opin. 2021 Mar;37(3):411-421. doi: 10.1080/03007995.2020.1847717. Epub 2021 Feb 1.


Introduction: Phenylketonuria (PKU) is a rare autosomal recessive disorder caused by a deficiency of phenylalanine hydroxylase (PAH). Its prevalence is estimated to be 1:10,000 in Europe. PKU is the commonest congenital inborn error of metabolism. The aim of our study was to investigate the characteristics of clinical practice in relation to PKU in Italy, in order to raise awareness about the current management and therapeutic approaches adopted.

Methods: Six Italian experts conducted a systematic literature review as well as an internal survey to investigate the relevant clinical aspects. Collectively, the expert panel managed a total of 678 PKU patients treated in the early stages of the condition over a 16-year period across six centers.

Results: The management of PKU varied markedly between centers, with differences in the composition of the multidisciplinary team, dietary treatments, compliance and adherence to management, tetrahydrobiopterin use, and patient follow-up. Patients were mostly managed by a pediatric reference center from the initial PKU diagnosis during newborn screening until adulthood, without transition to a specialized adult clinician. Fogginess, concentration reduction, low attention, anxiety, irritability, memory deficit, headache, and unstable mood were common features in patients with uncontrolled blood phenylalanine levels (generally above 600 ┬Ámol/L).

Conclusion: A homogeneous and shared approach to the management of PKU patients is important. Our survey demonstrates the current management of PKU in Italy, with the aim of promoting the implementation of therapeutic strategies and follow-up, increased patient compliance and adherence, and the achievement of the phenylalanine level targets recommended by European Union guidelines. Emerging therapies are likely to become a standard treatment for patients unable to comply with diet therapy and maintain their phenylalanine levels below the threshold values.

Supplemental data for this article is available online at

Keywords: BH4 testing; Italian survey; Phenylketonuria; adult; compliance; neurocognitive; transition.

Publication types

  • Research Support, Non-U.S. Gov't
  • Systematic Review

MeSH terms

  • Adult
  • Europe
  • Humans
  • Italy / epidemiology
  • Phenylalanine*
  • Phenylketonurias* / epidemiology
  • Phenylketonurias* / therapy
  • Surveys and Questionnaires


  • Phenylalanine