The blood is sent to a laboratory where results will be available in about two days. In the urine test, the patient is asked to urinate into a collecting cup. For an infant, the urine is collected in a pediatric urine collector. The process is painless. The length of time the test takes is determined by how long it takes the patient to urinate.
Results also take about two days.
Both these tests use thin layer chromatography to separate the amino acids present. Using this technique, the amino acids form a characteristic patterns on a glass plate coated with a thin layer of silica gel. This pattern is then compared to the normal pattern to determine if there are abnormalities. Preparation Before the blood test, the patient must not eat or drink for four hours. Failure to fast will alter the results of the test.