Children with PKU are perfectly normal at birth only they are incapable of satisfactorily converting the vital amino acid, phenylalanine, to another amino acid, tyrosine, like the human body is normally able to.
When a child is born it is the midwife's responsibility to have a blood sample taken. Until 2002, the most widespread analytical method was the so-called "heel prick test" or the Guthrie test. This test is performed on all newborn babies within the first five to seven days of their lives on a routine basis.
Today, the mother and her baby are normally discharged from the hospital earlier than this and so the midwife must see to it that the test is performed before. This can either be done at home or at the hospital.
