[Tetrahydrobiopterin therapy for hyperphenylalaninemia due to phenylalanine hydroxylase deficiency. When and how?].
| Autor: | Baldellou Vázquez A; Unidad de Enfermedades Metabólicas, Hospital Infantil Miguel Servet, Zaragoza, Spain. abaldellou@salud.aragon.es, Salazar García-Blanco MI, Ruiz-Echarri Zalaya MP, Campos Calleja C, Ruiz Desviat L, Ugarte Pérez M |
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| Jazyk: | Spanish; Castilian |
| Zdroj: | Anales de pediatria (Barcelona, Spain : 2003) [An Pediatr (Barc)] 2006 Feb; Vol. 64 (2), pp. 146-52. |
| DOI: | 10.1157/13084174 |
| Abstrakt: | Introduction: Some patients with hyperphenylalaninemia due to phenylalanine hydroxylase deficiency respond with a variable decrease in plasma phenylalanine levels after oral tetrahydrobiopterin (BH4) administration and are then able to tolerate higher dietary phenylalanine intake or even to discontinue a phenylalanine-restricted diet. BH4-sensitive patients are usually identified by means of a BH4 loading test, but consensus on the methodology of this test and the interpretation of its results is lacking. Consequently, a simple tool to identify which patients are likely candidates for this treatment and how they will progress in the long-term is required. Material and Methods: A combined oral BH4 loading test with phenylalanine (100 mg/kg) and BH4 (20 mg/kg) was performed in 20 patients with hyperphenylalaninemia under dietary phenylalanine restriction. Results: Independently of the genotype, the result was positive in all the 9 patients whose maximum phenylalanine level at diagnosis was below 815 nmol/ml. Currently, they are under treatment with tetrahydrobiopterin doses of 7-15 mg/kg/day. All these patients have been able to increase their oral phenylalanine intake. Six are currently following a normal diet and the remaining three are close to reaching this goal. None of the patients with a maximum phenylalanine level at diagnosis higher than 938 nmol/ml responded to the BH4 loading test. Conclusions: The maximum phenylalanine level at diagnosis seems to be a simple and reliable method to predict response to BH4 treatment. A high percentage of BH4-sensitive patients are able to discontinue a phenylalanine-restricted diet after long-term tetrahydrobiopterin treatment. |
| Databáze: | MEDLINE |
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