Optimization of an HPLC method for phenylalanine and tyrosine quantization in dried blood spot

Patients affected by Phenylketonuria (PKU) require lifelong management based on phenylalanine (Phe) and tyrosine (Tyr) restricted intake or tetrahydrobiopterin (BH4) administration. Frequent monitoring of blood concentration of both amino acids during treatment is the key point for clinicians to achieve the best long-term neuropsychological outcome.

The present study develops and validates a rapid and simple method for Phe and Tyr quantization in dried blood spot (DBS) since this specimen has the advantage of being low invasive, easily withdrawn even at home and stable if mail-delivered. The validation studies showed the robustness of the method.

Serum and DBS samples from PKU patients were analyzed and compared, finding a good correlation of Phe and Tyr concentrations between the two different matrixes.