BH(4) therapy impacts the nutrition status and intake in children with phenylketonuria: 2-year follow-up.

The impact of tetrahydrobiopterin (BH(4)) treatment on phenylalanine tolerance, medical-food consumption, and nutrition status in patients with phenylketonuria (PKU) was investigated. Six children (5-12 years) with well-controlled PKU, responding to a BH(4) dose of 20 mg/kg per day, were assessed for 24 months. Mean dietary phenylalanine tolerance increased from 421 ± 128 to 1470 ± 455 mg/day. Height Z scores significantly improved from 0.25 ± 0.99 at baseline to 0.53 ± 1.16 at 24 months (p for trend < 0.001). Patients tolerated more phenylalanine and more intact protein and required less medical food (protein supplement). Improved linear growth and nutrition status was seen over the course of the 24-month follow-up. Due to the variation in phenylalanine tolerance, dietary recommendations should be tailored to the patient's individual requirements.