Final answer:
A test for PKU is processed by collecting blood into tubes with K2EDTA, centrifugation to obtain plasma, and quenching with methanol, or by adding FeCl3 to urine for immediate color reactions. PKU is a genetic disorder necessitating a low-phenylalanine diet to prevent neurological symptoms.
Step-by-step explanation:
When performing a test for phenylketonuria (PKU), the specimen should be processed using specific procedures depending on the type of sample. For testing via blood samples, blood is collected into tubes containing dipotassium ethylenediaminetetra-acetic acid (K2EDTA) and centrifuged to obtain plasma. Following this, two 1-mL aliquots are transferred to Nalgene tubes and quenched with 3 mL of methanol. For urine samples, a 10% FeCl3 solution can be added to the patient's fresh urine resulting in an emerald green colour that fades after 20 minutes, indicating the presence of phenylalanine.
PKU is a genetic disorder that affects approximately 1 in every 15,000 births in the United States, characterized by the lack of sufficient activity of the enzyme phenylalanine hydroxylase. Individuals with PKU are unable to break down the amino acid phenylalanine into tyrosine, leading to toxic levels of phenylalanine in the body and resulting in various neurological symptoms. A strict diet low in phenylalanine is critical for managing PKU.