Original articleDiagnosis of Cystic Fibrosis by Sweat Testing: Age-Specific Reference Intervals
Section snippets
Subjects
We recruited subjects with CF and control subjects for the study during the period February 1, 2005, to November 1, 2006.
Control Subjects
Participants were recruited through advertisements at The Royal Children's Hospital and from a local school. Participants without CF were screened with a purpose-designed health questionnaire to exclude a CF phenotype (respiratory diseases, gastrointestinal symptoms, heat stroke, and male infertility), family history of CF, and diseases known to affect sweat electrolyte
Subjects' Selection
A total of 340 participants were recruited (Figure 1; available at www.jpeds.com).
Control Subjects
There were 300 participants without CF aged 5 to 68 years. Three subjects were excluded because of a family history of CF, and 9 subjects were found to be ΔF508 carriers. Of the remaining 288 subjects, 11 had insufficient sweat on the first occasion, and for 2 subjects the analysis was not possible because of technical error. All of these subjects were asked for a repeat sweat test. Six subjects were excluded
Discussion
In this study, age-related RIs have been developed for sweat chloride and sodium concentrations from unrelated participants (5-68 years old) with no family history of CF, no conditions known to affect sweat chloride and sodium concentrations, and who were not ΔF508 carriers. The sweat stimulation, collection, and analysis was performed as recommended by using international guidelines.11, 12, 13 No overlap in sweat chloride concentrations was observed between the group with CF and the group
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Variability of the sweat test in children with Cystic Fibrosis previously CRMS/CFSPID: A retrospective monocenter experience
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2022, Journal of Cystic FibrosisCitation Excerpt :For these reasons, sweat Cl− concentration is a useful biomarker to assess CFTR function in vivo in patients with CFTR-RD. A SCC >= 60 mmol/L is suggestive of CF, while a SCC below 30 mmol/L makes CF unlikely, leaving an ‘intermediate range’ between 30 and 59 mmol/L [74]. Sweat Chloride Concentration increases slightly with age in both healthy subjects, and in individuals with CF [75,76]. Environmental factors may also influence SCC as was demonstrated in a study of 1761 twins/siblings with CF. Inter-subject differences in SCC was ascribed to the type of CFTR mutation (more than 50% of the variance), climate and family diet which contributed to 13% of the differences, and unique individual factors such as modifier genes or individual exposure factors (4% of the difference)[76].
The sweat chloride test has lived up to the changes in CF care
2022, Journal of Cystic FibrosisStandards of care guidance for sweat testing; phase two of the ECFS quality improvement programme
2022, Journal of Cystic FibrosisCitation Excerpt :In order to reduce the amount of QNS samples, it is advisable to perform a ST in full term infants after 2 weeks of age, or when weight exceeds 2 kg in preterm infants. No upper age limit is defined for ST in adults, but the increasing sweat electrolyte concentration in adults needs to be considered [12,13]. While a sweat test is an essential diagnostic tool, treatment should not be delayed or withheld from an infant who has a positive NBS result and signs/ symptoms of CF, if the sweat collection is insufficient.
When CFSPID becomes CF
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Supported by a Scientific Grant from the Australasian Association of Clinical Biochemists. The authors declare no conflicts of interest.