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Intra‐individual biological variation in sweat chloride concentrations in CF, CFTR dysfunction, and healthy pediatric subjects
Author(s) -
Cirilli Natalia,
Raia Valeria,
Rocco Ilaria,
De Gregorio Fabiola,
Tosco Antonella,
Salvadori Laura,
Sepe Angela Ornella,
Buzzetti Roberto,
Minicuci Nadia,
Castaldo Giuseppe
Publication year - 2018
Publication title -
pediatric pulmonology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.866
H-Index - 106
eISSN - 1099-0496
pISSN - 8755-6863
DOI - 10.1002/ppul.23992
Subject(s) - cystic fibrosis , sweat , sweat test , medicine , newborn screening , physiology , gastroenterology , pediatrics
Background The sweat test is one of the main diagnostic tools used in newborn screening programs and as a confirmatory test, in case of suspect of Cystic Fibrosis (CF). Since sweat chloride (Cl) concentration is also considered an appropriate parameter to explore the efficacy of CFTR modulators in clinical trials, it is crucial to evaluate the biological variability of this test in healthy and pathological conditions. The aim of this pilot study was to determine the intra‐individual biological variability of sweat Cl, both in healthy individuals and CF patients and to assess its correlation with diet, season, and menstrual cycle. Methods Thirty‐five out of 36 selected subjects (6‐18 years) were enrolled by 2 CF care centers and assigned to 3 cohorts: CF, CFTR‐related disorder (CFTR‐RD) and healthy volunteers. Each participant was subjected to eight sweat tests in different conditions and time of the year. Data were analyzed using linear mixed effects models for repeated measures, taking also into account intra‐individual correlations. Results We observed a high intra‐individual variability of sweat Cl, with the lowest mean CV% values among CF patients (20.21 in CF, 29.74 in CFTR‐RD, and 31.15 in healthy subjects). Gender and diet had no influence on sweat Cl variability, nor had pubertal age and menstrual phase. Conclusion Results of this pilot study confirmed that sweat Cl variability is high in CF patients, although non‐CF individuals displayed even higher mean CV% values. Season significantly influenced sweat test values only in CF patients, likely due to changes in their hydration status.