OBJECTIVES: To characterize abnormalities of brain function in patients with phenylketonuria (PKU) who had relaxed or stopped the dietary regimen and to test whetheroral high-dose tyrosine (Tyr) supplementation has a beneficial effect. DESIGN: Comparison with a control group; double-blind, placebo-controlled study comprising six test times; crossover treatment groups; oral high-dose Tyr therapy (100 mg/kg body weight per day) or placebo administration for 4 weeks. SUBJECTS:Twenty-four early-treated patients with PKU aged 20.8 (16 to 25) years; 24 control subjects. METHODS:Plasma concentrations of phenylalanine and Tyr were monitored. Neuropsychologic tasks, visual evoked potentials, and spectral analysis of electroencephalographic activity were used to evaluate brain function. RESULTS: When patients with PKU were compared with control subjects, deficits in certain aspects of brain function were confirmed (i.e., a decreased ability to sustain attention, prolonged latencies of visual evoked potential peaks N1 and P2, and a reduced amount of fast-wave activity on the electroencephalogram). Baseline plasma phenylalanine and Tyr concentrations were in the typical range of adult patients with PKU. The plasma Tyr concentration increased approximately 200% during Tyr supplementation, but no beneficial effects were observed. CONCLUSIONS: High-dose Tyr supplementation cannot be recommended as an "alternative" treatment for patients with PKU after relaxation or termination of strict dietary adherence.
RCT Entities:
OBJECTIVES: To characterize abnormalities of brain function in patients with phenylketonuria (PKU) who had relaxed or stopped the dietary regimen and to test whether oral high-dose tyrosine (Tyr) supplementation has a beneficial effect. DESIGN: Comparison with a control group; double-blind, placebo-controlled study comprising six test times; crossover treatment groups; oral high-dose Tyr therapy (100 mg/kg body weight per day) or placebo administration for 4 weeks. SUBJECTS: Twenty-four early-treated patients with PKU aged 20.8 (16 to 25) years; 24 control subjects. METHODS: Plasma concentrations of phenylalanine and Tyr were monitored. Neuropsychologic tasks, visual evoked potentials, and spectral analysis of electroencephalographic activity were used to evaluate brain function. RESULTS: When patients with PKU were compared with control subjects, deficits in certain aspects of brain function were confirmed (i.e., a decreased ability to sustain attention, prolonged latencies of visual evoked potential peaks N1 and P2, and a reduced amount of fast-wave activity on the electroencephalogram). Baseline plasma phenylalanine and Tyr concentrations were in the typical range of adult patients with PKU. The plasma Tyr concentration increased approximately 200% during Tyr supplementation, but no beneficial effects were observed. CONCLUSIONS: High-dose Tyr supplementation cannot be recommended as an "alternative" treatment for patients with PKU after relaxation or termination of strict dietary adherence.
Authors: K Ullrich; J Weglage; C Oberwittler; M Pietsch; B Fünders; H von Eckardstein; J P Colombo Journal: Eur J Pediatr Date: 1996-07 Impact factor: 3.183
Authors: R Matalon; K Michals-Matalon; G Bhatia; E Grechanina; P Novikov; J D McDonald; J Grady; S K Tyring; F Guttler Journal: J Inherit Metab Dis Date: 2006-09-21 Impact factor: 4.982