Concept
The neonatal heel prick is a blood collection procedure done on newborns. It consists of making a pinprick puncture in one heel of the newborn to collect their blood. This technique is used frequently as the main way to collect blood from neonates. Other techniques include venous or arterial needle sticks, cord blood sampling, or umbilical line collection. This technique is often utilized for the Guthrie test, where it is used to soak the blood into pre-printed collection cards known as Guthrie cards. The classical Guthrie test is named after Robert Guthrie, an American bacteriologist and physician who devised it in 1962. The test has been widely used throughout North America and Europe as one of the core newborn screening tests since the late 1960s. The test was initially a bacterial inhibition assay, but is gradually being replaced in many areas by newer techniques such as tandem mass spectrometry that can detect a wider variety of congenital diseases. The blood samples can be used for a variety of metabolic tests to detect genetic conditions, including: Immunoreactive trypsinogen to detect cystic fibrosis. Maple syrup urine disease (MSUD or Branched Chain Ketonuria) a rare disorder where an error in metabolism inhibits the breakdown of amino acid leucine, isoleucine and valine. It can impair brain development. Medium-chain acyl-coenzyme A dehydrogenase deficiency (MCADD) Phenylketonuria, a disorder where an error in amino acid metabolism can impair brain development (PKU) Sickle-cell disease Thyroid stimulating hormone (TSH) or Thyroxin (T4) to detect congenital hypothyroidism and hence prevent cretinism. Isovaleric acidemia (IVA) Homocystinuria (pyridoxine unresponsive) (HCU) 17-hydroxy-progesterone (17-OHP) to detect adrenogenital syndrome, also known as congenital adrenal hyperplasia Galactosemia The test uses the growth of a strain of bacteria on a specially-prepared agar plate as a sign for the presence of high levels of phenylalanine, phenylpyruvate, and/or phenyllactate.
