Neonatal heel prick
The neonatal heel prick or Guthrie test is a screening test done on newborns. It consists in making a pinprick puncture in one heel of the newborn and soaking 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 test to detect genetic condictions, including:
- Phenylketonuria, a disorder where an error in amino acid metabolism can impair brain development (PKU)
- Thyroid stimulating hormone (TSH) to detect congenital hypothyroidism and hence prevent cretinism.
- Immunoreactive Trypsinogen (IRT) to detect cystic fibrosis.
- Medium-chain acyl-coenzyme A dehydrogenase deficiency (MCADD)
- Sickle-cell disease 
- Biotinidase deficiency
- Congenital adrenal hyperplasia
It is recommended that the screening test be performed when the infant is between 48 and 72 hours of age. False positives and negatives can sometimes occur when the screening tests are performed before 48 hours.
With genetic tests becoming more common, a wide variety of tests may use the blood drawn by this method. Many neonatal units (SCBUs) now use this method to carry out the daily blood tests (blood count, electrolytes) required to check the progress of ill neonates.
- Heel stick wound
- Newborn screening
- Dried blood spot testing
- Guthrie Cards, Catalyst (ABC1), 29 May 2003.
- Julia A. McMillan; Ralph D. Feigin; Catherine DeAngelis; M. Douglas Jones (1 April 2006). Oski's pediatrics: principles & practice. Lippincott Williams & Wilkins. pp. 162–. ISBN 978-0-7817-3894-1. Retrieved 16 April 2010.
- Newborn screening guidelines, Government of Victoria, 13 December 2007.