Left undiagnosed and untreated, it can result in coma and death. For the blood screening procedure, a sample of blood from the newborn infant is captured on a piece of filter paper from a prick to the heel. The blood dries on the paper and is sent to a laboratory where several types of tests can be performed. This method of specimen collection and transport to the testing laboratory was first made popular with the use of the test for PKU developed by Dr. Robert Guthrie. Based on PKU screening success and automation of the procedure, tests for other disorders were developed that could be applied to the same filter paper specimen that was submitted for PKU screening.
Today there are few, if any, newborn screening programs which utilize urine testing.
Parents obtain the specimen by pressing a filter paper card onto the baby's wet diaper. For such testing a specimen kit is usually sent home with the parents when the baby leaves the hospital. In order to handle newborn screening efficiently and cost-effectively in smaller states, regional centers have been developed with adequately equipped and staffed laboratories where tests are performed on newborn blood specimens from all states in the region. In most other states, a single centralized laboratory is utilized. This concept of centralized laboratory testing also leads to improved reliability of the testing procedure and was particularly important when screening for hypothyroidism was implemented.