What is the Guthrie test?

Guthrie test is a blood test that is performed on newborn children. The test is used to detect inherited genetic disorders called phenylketonuria . The disorder is caused by a defect of the metabolic pathway that decomposes the amino acid phenylalanine. If it is not treated, phenylketonuria can cause serious intellectual disability and timely detection through this test is essential.

Also known as a bacterial inhibitory test Guthrie, the Guthrie test is widely used throughout Europe, North America and Australlasia. In some countries, the test is used to screen other diseases except phenylketonuria. Other conditions that can be tested for this include cystic fibrosis, congenital hypothyroidism and sickle anemia. Each of these additional conditions is proven for the use of another method, but the same blood sample can be used for all tests. Gist named Robert Guthrie. The test was originally designed to project the presence of phenylketonuria in newborns. When the presence of this metabolDiscovering soon after birth, the affected child may be protected from intellectual disabilities and other side effects with low -orthothein diet, which limits phenylalanine intake.

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Guthrie test detects elevated blood phenylalanine levels using bacterial culture that requires phenylalanine growth. For this test, a blood sample is taken on the sixth or seventh day after birth. It is important to wait several days after birth before a blood pattern to ensure accurate reading.

Blood sample is incubated with a bacterial species called bacillus subtilis and chemicals called B-2-Thienylalanine, which inhibits the growth of bacteria acting as a phenylalanine agonist. This means that it prevents bacteria from feeding phenylalanine available in the culture medium. Blood sample from a child with phenylketonuria provides enough extra phenylalanine for bacteria growth despite the presence of Agonist B-2-Thienylalanine.

Therefore, a positive guthrie test for phenylketonuria is a test in which bacterial culture is able to grow. When bacterial culture cannot grow, the test is negative. When a positive test result is obtained, the child's doctor is contacted. The doctor will then arrange further testing to determine why phenylalanine levels are raised. This is an important consideration because phenylketonuria is less than 10% of the positive results of the Guthrie test. For example, false positive results can be achieved from infants born prematurely or with which antibiotics were treated in the week after birth.