A Mother of a Newborn Is Asking About the Guthrie

A mother of a newborn is asking about the Guthrie test. Which of the following responses made by the nurse is the least accurate?

A) This test determines the presence of enzymes that process phenylalanine in the blood.
B) A high level of phenylalanine is clinically significant.
C) The infant must have taken milk before blood is extracted.
D) The test is done every year to track the progress of disease.