Real-life application of a point-of-care biosensor for phenylalanine in patients with phenylketonuria

Phenylketonuria (PKU) is a rare metabolic disorder characterized by elevated phenylalanine (PHE) levels, requiring lifelong dietary management and regular monitoring. Current PHE monitoring methods, such as tandem mass spectrometry (FIA-MS/MS), are laboratory-dependent, necessitating sample transport and causing delays in result delivery. This emphasizes the need for point-of-care (PoC) solutions. We developed a bioluminescence-based PHE sensor integrated with the phenyx smartphone app for real-time monitoring and data sharing. A clinical study involving 47 PKU patients compared at-home sensor measurements with dried blood spots (DBS) analyzed by FIA-MS/MS. The sensor results were slightly higher than FIA-MS/MS, with a mean difference of 1.4 mg/dL (84.7 µmol/L). Variability in measurements was influenced by test supervision (clinic vs. home) and test kit age (larger differences with older kits, p = 0.001). The sensor and app demonstrated feasibility, analytical reliability, and comparable performance to FIA-MS/MS, providing a potential platform for patient self-testing and improved PHE monitoring.