Clinical Chemistry in Paediatrics

Abstract

Clinical chemistry in the arena of paediatrics often involves some special concerns which are not commonly encountered in laboratories that perform testing on primarily adult populations. Being aware of these potential problems and the major differences between the two types of laboratories is important. A laboratory with an adult clientele will occasionally encounter specimens from paediatric patients and being conscious of possible issues allows the laboratory to respond correctly when they arise. The purpose of this article is to discuss basic day to day operational issues facing a chemistry laboratory in a paediatric setting, including several topics related to sample volume concerns and their effect on work flow. The article then describes the most noticeable differences in test menu and testing practices found between paediatric and adult institutions.

Key Concepts:

  • Paediatric patients have limited blood volume which restricts the sample volumes which are available for testing.

  • Test results from paediatric patients must be interpreted using age‐ and gender‐related reference intervals.

  • Testing for Inborn Errors of Metabolism is commonly performed in‐house in paediatric laboratories.

  • Sweat chloride testing is a common test in a paediatric laboratory and is still used to diagnose Cystic Fibrosis.

Keywords: paediatric clinical chemistry; sample volume; inborn errors of metabolism testing; sweat chloride; paediatric reference intervals

Figure 1.

Collection tube types commonly encountered in a paediatric lab, including: (a) microtainer tubes or ‘bullets’ – total volume <1.0 mL, (b) tube that is the size of a 5 mL tube with a built in insert and a capacity of <1.0 mL, and (c) regular 5 mL tube.

Figure 2.

Example of a workaround. Small sample cups which hold a maximum of 1.0 mL of sample (a) can be placed inside a regular 12×75 mm plastic tube (b). The resulting tube in a tube (c) can be bar‐coded, but both tubes must be labelled.

Figure 3.

Upper limit of the normal reference interval versus age for males (‐•‐) and females (‐♦‐) compared to the upper limit of normal for adults (‐ ‐ ‐ ‐).

Figure 4.

Testosterone reference intervals versus developmental stage for males (dashed lines) and females (solid lines).

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Further Reading

Dietzen DJ, Bennett MJ and Wong ECC (2010) Biochemical and Molecular Basis of Pediatric Disease, 4th edn. Washington DC: AACC Press.

Green A, Morgan I and Gray J (2003) Neonatology & Laboratory Medicine. London: ACB Venture Publications.

Web Links

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University of Michigan Medical School. Guidance: blood draw guidelines. http://irb.duhs.duke.edu/wysiwyg/downloads/Blood_Collect_Policy_Statement_Revised.pdf Accessed 21 May, 2012.

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Jones, Patricia M(Jul 2012) Clinical Chemistry in Paediatrics. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1002/9780470015902.a0023398]