2015-10-132015-10-132011-06GIUGLIANI, Luciana et al. Responsividade à tetrahidrobiopterina em pacientes com deficiência de fenilalanina hidroxilase. Jornal de Pediatria, Porto Alegre, v. 87, n. 3, p. 245-251, jun. 2011. Disponível em: <http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0021-75572011000300011&lng=pt&nrm=iso>. Acesso em: 9 out. 2015. <http://dx.doi.org/10.2223/JPED.2090>.0021-7557https://repositorio.ufpa.br/handle/2011/6941Objective: To identify patients responsive to tetrahydrobiopterin (BH4) in a sample of Brazilians with hyperphenylalaninemia due to phenylalanine hydroxylase deficiency (HPA-PAH). Methods: Interventional study, convenience sampling. The inclusion criteria were: diagnosis of HPA-PAH; age ≥ 7 years; phenylalanine-restricted diet and phenylalanine (Phe) levels ≥ 6 mg/dL in all blood tests 1 year before inclusion. Blood samples were obtained the day before (day 1) and at 0, 4, 8 (day 2) and 24 h (day 3) after BH4 intake. Phe levels were measured using tandem mass spectrometry. The criteria used to define responsiveness to BH4 were: criterion 1- Phe reduction ≥ 30% 8 h after BH4 administration; criterion 2 - Phe reduction ≥ 30% 24 h after BH4 administration. Results: Eighteen patients were enrolled (median age, 14 years; 12 boys). Five patients were responsive to BH4, 3 according to both criteria (one classical PKU, two mild PKU); and two according to criterion 2 (one classical PKU; one indefinite PKU type). There were no differences between Phe serum levels on day 1 and at the other time points (p = 0.523). However, Phe levels on days 1 and 2 were significantly different (p = 0.006). The analysis of the phenotype-genotype association confirmed its multifactorial character. Conclusion: A relevant number of Brazilian patients with HPA-PAH are responsive to BH4, in agreement with other studies in the literature.porAcesso AbertoFenilcetonúriasFenilalanina hidroxilaseBiopterinaArtigo de Periódico