biostudies-literatureUnknown15(3)Oktem RM<h4>Background</h4>Hyperphenylalaninemia (HPA) is defined as blood phenylalanine (Phe) levels exceeding the normal values (>120 μmol/L or >2 mg/dL) and is caused by a deficiency in the enzyme phenylalanine hydroxylase (PAH). The widespread screening of Phe levels in newborn screening programs has led to a very high number of patients with HPA.<h4>Methods</h4>The samples were collected at various ages, not at the point of diagnosis. Nine pterin derivatives, including isoxanthopterin, sepiapterin, xanthopterin, primapterin, biopterin, neopterin, 7,8-dihydrobiopterin, 7,8-dihydroneopterin, and tetrahydrobiopterin (BH4), were analyzed in different HPA classes in serum, dried blood spots (DBS), and urine samples. A total of 18 patients, including six classical phenylketonuria (PKU), eight BH4-rMolecular syndromology185-193https://www.ebi.ac.uk/biostudies/studies/S-EPMC11149980biostudies-literaturePterin Profiling in Serum, Dried Blood Spot, and Urine Samples Using LC-MS/MS in Patients with Inherited Hyperphenylalaninemia.PMC11149980Oktem RMInci ABayrak HMavis MEYılmaz HEzgu FSGursu GGTumer LDemir FOkur IBiberoglu GfalsePterin Profiling in Serum, Dried Blood Spot, and Urine Samples Using LC-MS/MS in Patients with Inherited Hyperphenylalaninemia.<h4>Background</h4>Hyperphenylalaninemia (HPA) is defined as blood phenylalanine (Phe) levels exceeding the normal values (>120 μmol/L or >2 mg/dL) and is caused by a deficiency in the enzyme phenylalanine hydroxylase (PAH). The widespread screening of Phe levels in newborn screening programs has led to a very high number of patients with HPA.<h4>Methods</h4>The samples were collected at various ages, not at the point of diagnosis. Nine pterin derivatives, including isoxanthopterin, sepiapterin, xanthopterin, primapterin, biopterin, neopterin, 7,8-dihydrobiopterin, 7,8-dihydroneopterin, and tetrahydrobiopterin (BH4), were analyzed in different HPA classes in serum, dried blood spots (DBS), and urine samples. A total of 18 patients, including six classical phenylketonuria (PKU), eight BH4-r2024-01-01T00:00:00Z2024 Jun2025-04-18T16:01:25.133Z2025-04-07T02:58:30.071ZS-EPMC111499803884132910.1159/000535853