Tetrahydrobiopterin responsiveness in phenylketonuria: prediction with the 48-hour loading test and genotype.

ABSTRACT:

Background

How to efficiently diagnose tetrahydrobiopterin (BH4) responsiveness in patients with phenylketonuria remains unclear. This study investigated the positive predictive value (PPV) of the 48-hour BH4 loading test and the additional value of genotype.

Methods

Data of the 48-hour BH4 loading test (20 mg BH4/kg/day) were collected at six Dutch university hospitals. Patients with ≥30% phenylalanine reduction at ≥1 time points during the 48 hours (potential responders) were invited for the BH4 extension phase, designed to establish true-positive BH4 responsiveness. This is defined as long-term ≥30% reduction in mean phenylalanine concentration and/or ≥4 g/day and/or ≥50% increase of natural protein intake. Genotype was collected if available.

Results

177/183 patie

SUBMITTER: Anjema K 

PROVIDER: S-EPMC3711849 | biostudies-literature | 2013 Jul

REPOSITORIES: biostudies-literature