Phenylalanine and Tyrosine quantitative analysis in plasma (Phenylalanine and Tyrosine, Quantitative, Plasma - PKU) is an important medical test aimed at measuring the levels of the amino acids phenylalanine and tyrosine in the blood. This test is primarily used to diagnose phenylketonuria (PKU), a genetic disorder that affects the body’s ability to metabolize phenylalanine, which can lead to its accumulation in the body and cause serious health problems if not managed. It is recommended to perform this test early in life, usually as part of newborn screening, to monitor amino acid levels and determine the need for dietary or therapeutic interventions. The results help doctors make informed decisions regarding management of the condition and ensure the patient’s long-term health.