A reference interval for sweat chloride in infants aged between five and six weeks of age

R Jayaraj, P V Barton, P Newland, R Mountford, N J Shaw, E McCarthy, D M Isherwood, K W Southern

Research output: Contribution to journalArticle

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Abstract

Background: This study was designed to establish a reference interval for sweat chloride for infants without evidence of cystic fibrosis (CF), aged between 5 wk and 6 wk, a time when sweat testing is an integral part of newborn screening for CF. In addition, we compared the gold standard method of sweat testing (quantitative pilocarpine iontophoresis [QPIT, coulometry]) with an emerging methodology (MacroductTM [ISE]). Methods: This was a prospective study on healthy infants at 5–6 wk of age. Sweat collection was undertaken at home on both outer thigh areas using two methods (QPIT and MacroductTM). The order of testing was randomly assigned. Filter paper samples (QPIT) were analysed using flame photometry and coulometry. MacroductTM samples were analysed using ion-selective electrodes (ISE, Abbott Architect c8000, UK). Results: Insufficient sweat was collected on 28 occasions with the QPIT (coulometry) method and on 31 with the MacroductTM (ISE) capillary system. We achieved a 92% success rate in undertaking two sweat collections consecutively (n = 177). Sweat chloride concentrations were normally distributed with excellent limits of agreement between the two methods of sweat collection and analysis (n = 150). Median (IQR) sweat chloride was 11.2 mmol/L (8–13) with QPIT (coulometry) method with a 99.5th centile (n = 165) of 24 mmol/L. Conclusion: The MacroductTM (ISE) capillary sweat collection system is valid in this age group. Sweat chloride concentrations above 30 mmol/L should prompt assessment in a specialist CF centre.
Original languageEnglish
Pages (from-to)73-78
JournalAnnals of Clinical Biochemistry
Volume46
Issue number1
DOIs
Publication statusPublished - 2009

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Coulometers
Sweat
Chlorides
Testing
Photometry
Pilocarpine
Cystic Fibrosis
Screening
Ion-Selective Electrodes
Iontophoresis
Thigh

Cite this

Jayaraj, R., Barton, P. V., Newland, P., Mountford, R., Shaw, N. J., McCarthy, E., ... Southern, K. W. (2009). A reference interval for sweat chloride in infants aged between five and six weeks of age. Annals of Clinical Biochemistry, 46(1), 73-78. https://doi.org/10.1258/acb.2008.008081
Jayaraj, R ; Barton, P V ; Newland, P ; Mountford, R ; Shaw, N J ; McCarthy, E ; Isherwood, D M ; Southern, K W. / A reference interval for sweat chloride in infants aged between five and six weeks of age. In: Annals of Clinical Biochemistry. 2009 ; Vol. 46, No. 1. pp. 73-78.
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abstract = "Background: This study was designed to establish a reference interval for sweat chloride for infants without evidence of cystic fibrosis (CF), aged between 5 wk and 6 wk, a time when sweat testing is an integral part of newborn screening for CF. In addition, we compared the gold standard method of sweat testing (quantitative pilocarpine iontophoresis [QPIT, coulometry]) with an emerging methodology (MacroductTM [ISE]). Methods: This was a prospective study on healthy infants at 5–6 wk of age. Sweat collection was undertaken at home on both outer thigh areas using two methods (QPIT and MacroductTM). The order of testing was randomly assigned. Filter paper samples (QPIT) were analysed using flame photometry and coulometry. MacroductTM samples were analysed using ion-selective electrodes (ISE, Abbott Architect c8000, UK). Results: Insufficient sweat was collected on 28 occasions with the QPIT (coulometry) method and on 31 with the MacroductTM (ISE) capillary system. We achieved a 92{\%} success rate in undertaking two sweat collections consecutively (n = 177). Sweat chloride concentrations were normally distributed with excellent limits of agreement between the two methods of sweat collection and analysis (n = 150). Median (IQR) sweat chloride was 11.2 mmol/L (8–13) with QPIT (coulometry) method with a 99.5th centile (n = 165) of 24 mmol/L. Conclusion: The MacroductTM (ISE) capillary sweat collection system is valid in this age group. Sweat chloride concentrations above 30 mmol/L should prompt assessment in a specialist CF centre.",
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Jayaraj, R, Barton, PV, Newland, P, Mountford, R, Shaw, NJ, McCarthy, E, Isherwood, DM & Southern, KW 2009, 'A reference interval for sweat chloride in infants aged between five and six weeks of age', Annals of Clinical Biochemistry, vol. 46, no. 1, pp. 73-78. https://doi.org/10.1258/acb.2008.008081

A reference interval for sweat chloride in infants aged between five and six weeks of age. / Jayaraj, R; Barton, P V; Newland, P; Mountford, R; Shaw, N J; McCarthy, E; Isherwood, D M; Southern, K W.

In: Annals of Clinical Biochemistry, Vol. 46, No. 1, 2009, p. 73-78.

Research output: Contribution to journalArticle

TY - JOUR

T1 - A reference interval for sweat chloride in infants aged between five and six weeks of age

AU - Jayaraj, R

AU - Barton, P V

AU - Newland, P

AU - Mountford, R

AU - Shaw, N J

AU - McCarthy, E

AU - Isherwood, D M

AU - Southern, K W

PY - 2009

Y1 - 2009

N2 - Background: This study was designed to establish a reference interval for sweat chloride for infants without evidence of cystic fibrosis (CF), aged between 5 wk and 6 wk, a time when sweat testing is an integral part of newborn screening for CF. In addition, we compared the gold standard method of sweat testing (quantitative pilocarpine iontophoresis [QPIT, coulometry]) with an emerging methodology (MacroductTM [ISE]). Methods: This was a prospective study on healthy infants at 5–6 wk of age. Sweat collection was undertaken at home on both outer thigh areas using two methods (QPIT and MacroductTM). The order of testing was randomly assigned. Filter paper samples (QPIT) were analysed using flame photometry and coulometry. MacroductTM samples were analysed using ion-selective electrodes (ISE, Abbott Architect c8000, UK). Results: Insufficient sweat was collected on 28 occasions with the QPIT (coulometry) method and on 31 with the MacroductTM (ISE) capillary system. We achieved a 92% success rate in undertaking two sweat collections consecutively (n = 177). Sweat chloride concentrations were normally distributed with excellent limits of agreement between the two methods of sweat collection and analysis (n = 150). Median (IQR) sweat chloride was 11.2 mmol/L (8–13) with QPIT (coulometry) method with a 99.5th centile (n = 165) of 24 mmol/L. Conclusion: The MacroductTM (ISE) capillary sweat collection system is valid in this age group. Sweat chloride concentrations above 30 mmol/L should prompt assessment in a specialist CF centre.

AB - Background: This study was designed to establish a reference interval for sweat chloride for infants without evidence of cystic fibrosis (CF), aged between 5 wk and 6 wk, a time when sweat testing is an integral part of newborn screening for CF. In addition, we compared the gold standard method of sweat testing (quantitative pilocarpine iontophoresis [QPIT, coulometry]) with an emerging methodology (MacroductTM [ISE]). Methods: This was a prospective study on healthy infants at 5–6 wk of age. Sweat collection was undertaken at home on both outer thigh areas using two methods (QPIT and MacroductTM). The order of testing was randomly assigned. Filter paper samples (QPIT) were analysed using flame photometry and coulometry. MacroductTM samples were analysed using ion-selective electrodes (ISE, Abbott Architect c8000, UK). Results: Insufficient sweat was collected on 28 occasions with the QPIT (coulometry) method and on 31 with the MacroductTM (ISE) capillary system. We achieved a 92% success rate in undertaking two sweat collections consecutively (n = 177). Sweat chloride concentrations were normally distributed with excellent limits of agreement between the two methods of sweat collection and analysis (n = 150). Median (IQR) sweat chloride was 11.2 mmol/L (8–13) with QPIT (coulometry) method with a 99.5th centile (n = 165) of 24 mmol/L. Conclusion: The MacroductTM (ISE) capillary sweat collection system is valid in this age group. Sweat chloride concentrations above 30 mmol/L should prompt assessment in a specialist CF centre.

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DO - 10.1258/acb.2008.008081

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JO - Annals of Clinical Biochemistry

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SN - 0004-5632

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