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{{Short description|Blood collection procedure for newborns}} | {{Short description|Blood collection procedure for newborns}} | ||
[[File:Phenylketonuria testing.jpg|thumb|The blood of a two-week-old infant is collected for a [[ | {{Use dmy dates|date=June 2025}} | ||
[[File:Phenylketonuria testing.jpg|thumb|The blood of a two-week-old infant is collected for a [[phenylketonuria]], or PKU, screening]] | |||
The '''neonatal heel prick''' is a [[blood collection|blood collection procedure]] done on [[newborn]]s. It consists of making a pinprick puncture in one | The '''neonatal heel prick''' is a [[blood collection|blood-collection procedure]] done on [[newborn]]s. It consists of making a pinprick puncture in one heel of the newborn to collect their blood. This [[Medical procedure|technique]] is used frequently as the main way to collect blood from neonates. Other techniques include [[vein|venous]] or [[artery|arterial]] [[needle stick]]s, [[cord blood]] sampling, or [[umbilical line]] collection. This technique is often used for the '''Guthrie test''', where it is used to soak the blood into pre-printed collection cards known as Guthrie cards.<ref>[http://www.abc.net.au/catalyst/stories/s867619.htm Guthrie Cards] {{Webarchive|url=https://web.archive.org/web/20161201075845/http://www.abc.net.au/catalyst/stories/s867619.htm |date=1 December 2016 }}, ''[[Catalyst (TV program)|Catalyst]]'' ([[ABC1]]), 29 May 2003.</ref><ref name="McMillanFeigin2006">{{cite book|author1=Julia A. McMillan|author2=Ralph D. Feigin|author3=Catherine DeAngelis|author4=M. Douglas Jones|title=Oski's pediatrics: principles & practice|url=https://books.google.com/books?id=VbjFQiz8aR0C&pg=PA162|access-date=16 April 2010|date=1 April 2006|publisher=Lippincott Williams & Wilkins|isbn=978-0-7817-3894-1|pages=162–}}</ref> | ||
The classical Guthrie test is named after [[Robert Guthrie (microbiologist)|Robert Guthrie]], an American [[bacteriologist]] and | The classical Guthrie test is named after [[Robert Guthrie (microbiologist)|Robert Guthrie]], an American [[bacteriologist]] and physician who devised it in 1962. The test has been widely used in 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 disease]]s. | ||
==Detected diseases== | ==Detected diseases== | ||
| Line 13: | Line 14: | ||
* [[Medium-chain acyl-coenzyme A dehydrogenase deficiency]] (MCADD) | * [[Medium-chain acyl-coenzyme A dehydrogenase deficiency]] (MCADD) | ||
* [[Phenylketonuria]], a disorder where an error in [[amino acid]] [[metabolism]] can impair brain development (PKU) | * [[Phenylketonuria]], a disorder where an error in [[amino acid]] [[metabolism]] can impair brain development (PKU) | ||
* [[Sickle-cell disease]]<ref>{{cite web |url=http://www.screening.nhs.uk/an/index.htm |title=NHS Screening antenatal and newborn |access-date=2009-02-26 | * [[Sickle-cell disease]]<ref>{{cite web |url=http://www.screening.nhs.uk/an/index.htm |title=NHS Screening antenatal and newborn |access-date=2009-02-26 |archive-url=https://web.archive.org/web/20090212181713/http://www.screening.nhs.uk/an/index.htm |archive-date=2009-02-12 }}</ref> | ||
* [[Thyroid stimulating hormone]] (TSH) or [[Thyroxin]] (T4) to detect [[congenital hypothyroidism]] and hence prevent [[cretinism]]. | * [[Thyroid stimulating hormone]] (TSH) or [[Thyroxin]] (T4) to detect [[congenital hypothyroidism]] and hence prevent [[cretinism]]. | ||
* [[Isovaleric acidemia]] (IVA) | * [[Isovaleric acidemia]] (IVA) | ||
| Line 21: | Line 22: | ||
==Mechanism== | ==Mechanism== | ||
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. The compound B-2-thienylalanine will inhibit the growth of the bacterium ''Bacillus subtilis'' (ATCC 6051) on minimal culture media. If phenylalanine, phenylpyruvate, and/or phenyllactate is added to the medium, then growth is restored. Such compounds will be present in excess in the blood or urine of patients with PKU. If a suitably-prepared sample of blood or urine is applied to the seeded agar plate, the growth of the bacteria in the test will be a positive indicator for PKU in the patient.<ref name=uic>{{cite web|url=http://www.uic.edu/classes/phar/phar332/Clinical_Cases/aa%20metab%20cases/PKU%20Cases/PHE-TST001.htm |title=PHE-TST001 |work=uic.edu | 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. The compound B-2-thienylalanine will inhibit the growth of the bacterium ''Bacillus subtilis'' (ATCC 6051) on minimal culture media. If phenylalanine, phenylpyruvate, and/or phenyllactate is added to the medium, then growth is restored. Such compounds will be present in excess in the blood or urine of patients with PKU. If a suitably-prepared sample of blood or urine is applied to the seeded agar plate, the growth of the bacteria in the test will be a positive indicator for PKU in the patient.<ref name=uic>{{cite web|url=http://www.uic.edu/classes/phar/phar332/Clinical_Cases/aa%20metab%20cases/PKU%20Cases/PHE-TST001.htm |title=PHE-TST001 |work=uic.edu |archive-url=https://web.archive.org/web/20130927101945/http://www.uic.edu/classes/phar/phar332/Clinical_Cases/aa%20metab%20cases/PKU%20Cases/PHE-TST001.htm |archive-date=2013-09-27 }}</ref> | ||
To prepare the sample for application, a small amount of blood (from a heel puncture, for example) or urine (from a diaper, for example) is applied to a piece of filter paper. Then a small disc is punched from the center of the spot of blood or urine, and the disc applied to the surface of a seeded, minimal-medium agar plate that contains added beta-2-thienylalanine. If the sample contains phenylalanine, phenylpyruvate, and/or phenyllactate then these compounds will diffuse into the agar medium. If their concentrations are high enough (as with the excess levels seen with PKU), bacteria will grow under the disc, but not elsewhere. Generally an overnight incubation is enough to determine whether phenylalanine, phenylpyruvate, and/or phenyllactate are present in unusual concentrations in blood or urine.<ref name=uic /> | To prepare the sample for application, a small amount of blood (from a heel puncture, for example) or urine (from a diaper, for example) is applied to a piece of filter paper. Then a small disc is punched from the center of the spot of blood or urine, and the disc applied to the surface of a seeded, minimal-medium agar plate that contains added beta-2-thienylalanine. If the sample contains phenylalanine, phenylpyruvate, and/or phenyllactate then these compounds will diffuse into the agar medium. If their concentrations are high enough (as with the excess levels seen with PKU), bacteria will grow under the disc, but not elsewhere. Generally an overnight incubation is enough to determine whether phenylalanine, phenylpyruvate, and/or phenyllactate are present in unusual concentrations in blood or urine.<ref name=uic /> | ||
| Line 28: | Line 29: | ||
The blood spot sample should be taken between 48 and 72 hours of age for all babies regardless of medical condition, milk feeding and prematurity. For the purpose of screening, date of birth is day 0 (some IT systems record date of birth as day 1).<ref>{{cite web|url=http://newbornbloodspot.screening.nhs.uk/standards|title=Standards|work=screening.nhs.uk|access-date=2015-02-07|archive-date=2009-05-01|archive-url=https://web.archive.org/web/20090501152642/http://newbornbloodspot.screening.nhs.uk/standards|url-status=live}}</ref> [[False positive]]s and [[false negative]]s can sometimes occur when the screening tests are performed before 48 hours.<ref>{{cite web|url=http://www.health.vic.gov.au/genetics/nbs.htm |title=Newborn screening guidelines |work=health.vic.gov.au (via archive.org) |url-status=bot: unknown |archive-url=https://web.archive.org/web/20060308182225/http://www.health.vic.gov.au/genetics/nbs.htm |archive-date=2006-03-08 }}</ref> | The blood spot sample should be taken between 48 and 72 hours of age for all babies regardless of medical condition, milk feeding and prematurity. For the purpose of screening, date of birth is day 0 (some IT systems record date of birth as day 1).<ref>{{cite web|url=http://newbornbloodspot.screening.nhs.uk/standards|title=Standards|work=screening.nhs.uk|access-date=2015-02-07|archive-date=2009-05-01|archive-url=https://web.archive.org/web/20090501152642/http://newbornbloodspot.screening.nhs.uk/standards|url-status=live}}</ref> [[False positive]]s and [[false negative]]s can sometimes occur when the screening tests are performed before 48 hours.<ref>{{cite web|url=http://www.health.vic.gov.au/genetics/nbs.htm |title=Newborn screening guidelines |work=health.vic.gov.au (via archive.org) |url-status=bot: unknown |archive-url=https://web.archive.org/web/20060308182225/http://www.health.vic.gov.au/genetics/nbs.htm |archive-date=2006-03-08 }}</ref> | ||
When the [[immunoassay]] method is | When the [[immunoassay]] method is used as a screening method for quantifying [[17α-hydroxyprogesterone]] (17OHP) in dried blood spots, it exhibits a significant rate of false positive results. As per the clinical practice guideline issued by the Endocrine Society in 2018, employing [[LC-MS/MS]] to measure 17OHP and other adrenal steroid hormones (such as [[21-deoxycortisol]] and androstenedione) is recommended as a supplementary screening approach to enhance the accuracy of positive predictions.<ref name="pmid38169194">{{cite journal |vauthors=Mu D, Sun D, Qian X, Ma X, Qiu L, Cheng X, Yu S |title=Steroid profiling in adrenal disease |journal=Clin Chim Acta |volume=553 |issue= |article-number=117749 |date=December 2023 |pmid=38169194 |doi=10.1016/j.cca.2023.117749 |url=}}</ref> | ||
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.{{citation needed|date=June 2020}} | 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.{{citation needed|date=June 2020}} | ||
==Data retention controversy== | ==Data retention controversy== | ||
In | In Ireland, a controversy emerged in 2012 whereby a number of hospitals retained heel prick test cards and thereby a [[DNA database]] with over a million samples from 1984, without parental consent or [[Parental notification|notification]]. This resulted in the introduction of a ten-year rolling destruction cycle. Similar practices exist in the United Kingdom, New Zealand, and several states of the United States.<ref>{{cite web|url=http://www.irishtimes.com/news/international-standards-for-storing-samples-vary-wildly-1.474167|title=International standards for storing samples vary wildly|work=Irish Times|access-date=2015-03-25|archive-date=2015-04-02|archive-url=https://web.archive.org/web/20150402104723/http://www.irishtimes.com/news/international-standards-for-storing-samples-vary-wildly-1.474167|url-status=live}}</ref> | ||
==Heel stick wound== | ==Heel stick wound== | ||
Heel stick | Heel stick wounds are a [[cutaneous condition]] characterized by a break in the skin caused by neonatal heel prick.<ref name="Bolognia">{{cite book |author=Rapini, Ronald P. |author2=Bolognia, Jean L. |author3=Jorizzo, Joseph L. |title=Dermatology: 2-Volume Set |publisher=Mosby |location=St. Louis |year=2007 |isbn=978-1-4160-2999-1 }}</ref> The heel stick is an important medical screening for the child and causes [[Pain scale|low levels of pain]].<ref>{{cite book|last1=Perry|first1=Shannon E.|title=Maternal Child Nursing Care in Canada - E-Book|date=2016|publisher=Elsevier Health Sciences|isbn=978-1-77172-083-0|page=700|url=https://books.google.com/books?id=qtcoDwAAQBAJ&q=Heel+stick+wound|access-date=18 January 2018|language=en}}</ref> | ||
== See also ==<!-- PLEASE RESPECT ALPHABETICAL ORDER --> | == See also ==<!-- PLEASE RESPECT ALPHABETICAL ORDER --> | ||
Latest revision as of 14:54, 20 October 2025
Template:Short description Template:Use dmy dates
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 used for the Guthrie test, where it is used to soak the blood into pre-printed collection cards known as Guthrie cards.[1][2]
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 in 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.
Detected 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[3]
- 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
Mechanism
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. The compound B-2-thienylalanine will inhibit the growth of the bacterium Bacillus subtilis (ATCC 6051) on minimal culture media. If phenylalanine, phenylpyruvate, and/or phenyllactate is added to the medium, then growth is restored. Such compounds will be present in excess in the blood or urine of patients with PKU. If a suitably-prepared sample of blood or urine is applied to the seeded agar plate, the growth of the bacteria in the test will be a positive indicator for PKU in the patient.[4]
To prepare the sample for application, a small amount of blood (from a heel puncture, for example) or urine (from a diaper, for example) is applied to a piece of filter paper. Then a small disc is punched from the center of the spot of blood or urine, and the disc applied to the surface of a seeded, minimal-medium agar plate that contains added beta-2-thienylalanine. If the sample contains phenylalanine, phenylpyruvate, and/or phenyllactate then these compounds will diffuse into the agar medium. If their concentrations are high enough (as with the excess levels seen with PKU), bacteria will grow under the disc, but not elsewhere. Generally an overnight incubation is enough to determine whether phenylalanine, phenylpyruvate, and/or phenyllactate are present in unusual concentrations in blood or urine.[4]
Timing
The blood spot sample should be taken between 48 and 72 hours of age for all babies regardless of medical condition, milk feeding and prematurity. For the purpose of screening, date of birth is day 0 (some IT systems record date of birth as day 1).[5] False positives and false negatives can sometimes occur when the screening tests are performed before 48 hours.[6]
When the immunoassay method is used as a screening method for quantifying 17α-hydroxyprogesterone (17OHP) in dried blood spots, it exhibits a significant rate of false positive results. As per the clinical practice guideline issued by the Endocrine Society in 2018, employing LC-MS/MS to measure 17OHP and other adrenal steroid hormones (such as 21-deoxycortisol and androstenedione) is recommended as a supplementary screening approach to enhance the accuracy of positive predictions.[7]
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.Script error: No such module "Unsubst".
Data retention controversy
In Ireland, a controversy emerged in 2012 whereby a number of hospitals retained heel prick test cards and thereby a DNA database with over a million samples from 1984, without parental consent or notification. This resulted in the introduction of a ten-year rolling destruction cycle. Similar practices exist in the United Kingdom, New Zealand, and several states of the United States.[8]
Heel stick wound
Heel stick wounds are a cutaneous condition characterized by a break in the skin caused by neonatal heel prick.[9] The heel stick is an important medical screening for the child and causes low levels of pain.[10]
See also
References
External links
- Heel prick test at the General Practice Notebook
Template:Tests relating to nutrition
- ↑ Guthrie Cards Template:Webarchive, Catalyst (ABC1), 29 May 2003.
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