Defining tetrahydrobiopterin responsiveness in phenylketonuria: Survey results from 38 countries


Background: A subset of patients with phenylketonuria benefit from treatment with tetrahydrobiopterin (BH 4), although there is no consensus on the definition of BH 4 responsiveness. The aim of this study therefore was to gain insight into the definitions of long-term BH 4 responsiveness being used around the world. Methods: We performed a web-based survey targeting healthcare professionals involved in the treatment of PKU patients. Data were analysed according to geographical region (Europe, USA/Canada, other). Results: We analysed 166 responses. Long-term BH 4 responsiveness was commonly defined using natural protein tolerance (95.6%), improvement of metabolic control (73.5%) and increase in quality of life (48.2%). When a specific value for a reduction in phenylalanine concentrations was reported (n = 89), 30% and 20% were most frequently used as cut-off values (76% and 19% of respondents, respectively). When a specific relative increase in natural protein tolerance was used to define long-term BH 4 responsiveness (n = 71), respondents most commonly reported cut-off values of 30% and 100% (28% of respondents in both cases). Respondents from USA/Canada (n = 50) generally used less strict cut-off values compared to Europe (n = 96). Furthermore, respondents working within the same center answered differently. Conclusion: The results of this study suggest a very heterogeneous situation on the topic of defining long-term BH 4 responsiveness, not only at a worldwide level but also within centers. Developing a strong evidence- and consensus-based definition would improve the quality of BH 4 treatment.

Publication DOI:
Divisions: College of Health & Life Sciences > School of Psychology
College of Health & Life Sciences > Clinical and Systems Neuroscience
College of Health & Life Sciences > School of Optometry > Vision, Hearing and Language
College of Health & Life Sciences
Additional Information: © 2021 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY license
Uncontrolled Keywords: International,Phenylketonuria,Survey,Tetrahydrobiopterin,Genetics,Endocrinology,Molecular Biology,Biochemistry,Endocrinology, Diabetes and Metabolism
Publication ISSN: 1096-7206
Last Modified: 30 Apr 2024 07:24
Date Deposited: 08 Mar 2021 10:06
Full Text Link:
Related URLs: https://www.sci ... 0330?via%3Dihub (Publisher URL)
http://www.scop ... tnerID=8YFLogxK (Scopus URL)
PURE Output Type: Article
Published Date: 2021-04
Published Online Date: 2021-02-04
Accepted Date: 2021-01-29
Authors: Evers, R A F
van Wegberg, A M J
Ahring, K
Beblo, S
Bélanger-Quintana, A
Bosch, A M
Burlina, A
Campistol, J
Coskun, T
Feillet, F
Giżewska, M
Huijbregts, S C J
Kearney, S
Langeveld, M
Leuzzi, V
Maillot, F
Muntau, A C
Rocha, J C
Romani, C (ORCID Profile 0000-0002-5693-4131)
Trefz, F K
MacDonald, A
van Spronsen, F J



Version: Published Version

License: Creative Commons Attribution

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