Transitioning of protein substitutes in patients with phenylketonuria: a pilot study.

Abstract

Introduction: In phenylketonuria (PKU), there is limited information about transitioning between protein substitutes and the influencing factors, particularly in young children. This pilot study assessed the stepwise transition from second to third-stage protein substitutes in children with PKU, aged 3-5 years.

Methods: Demographics, child behavior, maternal anxiety, and food neophobia scores were collected at baseline, mid-transition, and final assessment. Blood phenylalanine (Phe) was collected from 6 months pre-baseline to post-final assessment.

Results: Twelve children (n = 4 males, 33%, median age 3.2 years) participated. Sixty-seven percent (n = 8) transitioned to liquid amino acid-based protein substitute and 33% (n = 4) to glycomacropeptide (cGMP) powder. Forty-two percent (n = 5/12) had a smooth transition (Group 1, median 3.5 months), while the remaining faced difficulty (n = 3, 25%, Group 2), or failed full transition (n = 4, 33%, Group 3). In Groups 2 and 3, caregivers failed to follow instructions, demonstrating inconsistencies and child resistance. Group 2 children had significantly higher blood Phe levels (above 360 μmol/L), that was significantly higher than Groups 1 and 3 (p < 0.01), with Groups 1 and 3 maintaining blood Phe within target (p < 0.01). Higher maternal education and nursery/school attendance significantly influenced transition success (p < 0.05). No significant differences were found in child neophobia, maternal anxiety, or child behavior (p > 0.05). Mothers generally reported satisfaction with the stepwise transition process.

Conclusion: A stepwise transition to third-stage protein substitutes in PKU is effective, but is dependent on child metabolic control, parental education, and nursery/school support.