Please read the disclaimer.
The Metabolic Newborn Screen, also known as the heal stick or prick test, also known as the PKU screens your baby for disorders that are not part of the genetic testing that can be done during pregnancy. It is done by poking the baby’s heal and making it bleed, much like a finger prick to test blood sugar. The blood is collected on a specially treated paper and sent to a lab in Baton Rouge. The lab screens for 28 different disorders. A full list of the disorders with their descriptions can be viewed on the Louisiana Dept. of Health website here.
Make note; a screen determines there is a greater likelihood that a condition might exist, while a test determines whether the condition does exists or not.
Some states, like Louisiana, perform one newborn screen, usually when the baby is one to three days old. By this time, the baby has had time to eat and have a bowel movement, time to metabolize the meal. Most disorders can be detected by this amount of time. There is a very slight chance that a disorder may be missed. However, early detection is crucial so the treatment can begin before the disorder has a chance to do any organ damage to the baby.
Other states, such as our neighbor Texas, do the early screen at day one for early detection and another screen at two weeks for any disorders that may have been too early to detect during the first screen.
In my opinion, performing two screen would be more thorough for the metabolic disorders. However, I understand that a visit to a pediatrician when the baby is two weeks old can pose risks of exposure to other illnesses.