Quality of sweat test (ST) based on the proportion of sweat sodium (Na) and sweat chloride (Cl) as diagnostic parameter of cystic fibrosis: are we on the right way?

Faria, Alethéa Guimarães; Marson, Fernando Augusto Lima; Gomez, Carla Cristina de Souza; Ribeiro, Maria Ângela Gonçalves de Oliveira; Morais, Lucas Brioschi; Servidoni, Maria de Fátima; Bertuzzo, Carmen Sílvia; Sakano, Eulália; Goto, Maura Mikie Fukujima; Paschoal, Ilma Aparecida; Pereira, Mônica Corso; Hessel, Gabriel; Levy, Carlos Emílio; Toro, Adyléia Aparecida Dalbo Contrera; Peixoto, Andressa Oliveira; Simões, Maria Cristina Ribeiro dos Santos; Lomazi, Elizete Aparecida; Nogueira, Roberto José Negrão; Ribeiro, A.F.; Ribeiro, José Dirceu

doi:10.1186/s13000-016-0555-6

Cited by 5 publications

(6 citation statements)

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“…( 15 , 19 ); (ii) Is it necessary to measure sweat chloride alone or together with the analysis of sweat sodium? ( 15 , 20 ); (iii) Which are the most appropriate types of waves and current intensity to stimulate sweating in the ST? ( 4 ); (iv) How are the ST stages performed at different reference centers?…”

Section: Discussionmentioning

confidence: 99%

“…The association between sweat chloride and sweat sodium parameter to the ST quality control was analyzed by us previously, and we considered that the sweat sodium may be an indicative for quality discrimination, mainly in cases of doubts regarding the sweat chloride values ( 20 ). Even so, other studies should be done to clarify the biological variability, considering both ions dosage, observed in the ST among subjects that performed the test.…”

Section: Discussionmentioning

confidence: 99%

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Thirty Years of Sweat Chloride Testing at One Referral Center

et al. 2017

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ObjectiveTo conduct a descriptive analysis of the sweat test (ST), associating ST results with epidemiological data, CFTR (cystic fibrosis transmembrane conductance regulator) mutations and reasons to indicate the ST, as well as correlating sweat sodium and sweat chloride concentrations in subjects.MethodsRetrospective survey and descriptive analysis of 5,721 ST at a university referral center.ResultsThe inclusion of the subjects was based on clinical data related with cystic fibrosis (CF) phenotype. The samples were grouped by (i) sweat chloride concentrations (mEq/L): <30: 3,249/5,277 (61.6%); ≥30 to <60: 1,326/5,277 (25.1%); ≥60: 702/5,277 (13.3%) and (ii) age: (Group A––GA) 0 to <6 months; (Group B––GB) ≥6 months to <18 years; (Group C––GC) ≥18 years. Digestive symptoms showed higher prevalence ratio for the CF diagnosis as well as association between younger age and higher values of sweat chloride, sweat sodium, and chloride/sodium ratio. The indication of ST due to respiratory symptoms was higher in GB and associated with greater age, lower values of sweat chloride, sweat sodium, and chloride/sodium ratio. There was higher prevalence of ST with sweat chloride levels <30 mEq/L in GB, ≥60 mEq/L in GC, and with borderline level in GB. There was positive correlation between sweat sodium and sweat chloride. Sweat chloride/sweat sodium and sweat sodium–sweat chloride indexes showed association with sex, reason for ST indication, and CFTR mutations. Sex alters some values presented in the ST. The number of ST/year performed before and after the newborn screening implementation was the same; however, we observed a higher number of borderlines values. A wide spectrum of CFTR mutation was found. Severe CFTR mutations and F508del/F508del genotype were associated with highest probability of ST chloride levels ≥60 mEq/L, and the absence of CFTR mutations identified was associated with borderline ST and respiratory symptoms.ConclusionsST data showed wide variability dependent on age, sex, reason for examination indication, CFTR mutations, and weight of the collected sweat sample. Sweat sodium concentration is directly correlated with sweat chloride levels and it could be used as a quality parameter.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Thirty Years of Sweat Chloride Testing at One Referral Center

et al. 2017

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“…However, the measurement of Cl - , Na + and K + in sweat could improve the diagnosis of CF and reduce the number of false positive or negative results [7], [16]. In the study of Faria et al [19], the quality of the sweat test is based on the proportion of sweat sodium and chloride. Recently, several studies [20] have confirmed an analytical variation that may impact the clinical interpretation.…”

Section: Resultsmentioning

confidence: 99%

Sweat chloride quantification using capillary electrophoresis

Dubot

Liang²,

Dubs³

et al. 2019

Practical Laboratory Medicine

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BackgroundCystic fibrosis (CF) is the less rare and severe genetic disease among the European population. Biochemical diagnosis of CF is based on the demonstration of increased chloride concentration in sweat samples, obtained during the sweat test (ST). WynSep developed a capillary electrophoresis with contactless conductivity detection (CE-C4D) able to measure sweat chloride with a low sample volume. We evaluated the clinical feasibility of this device in a cohort of patients suspected of CF, in comparison with the common coulometric method (ChloroChek chloridometer).MethodsWe determined sweat chloride concentration of 65 samples from patients referred to our institution to undergo a sweat test. Each sample was submitted to coulometric method first, then WynSep-CE, with or without internal standard (IS) subject to sufficient volume sample.ResultsA total of 53 samples were analysed by both coulometric and WynSep-CE (using IS) methods. The method validation showed comparable analytical performances for both methods; no false positive or false negative was recorded. The two methods showed a high correlation (r = 0.993, p < 0.001) and a close agreement was demonstrated by two different statistical tests (Bland-Altman and Passing-Bablok).ConclusionsWynSep-CE is an accurate, fast, easy-to-use and an appropriate method for CF diagnosis.

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“…This fact influences the induction of sweat and, consequently, the sweat weight, promoting a variability at the sweat test results. In addition, gender and ethnicity may influence the natural variation of sweat test values and should be considered when conducting the test [ 25 – 27 ].…”

Section: Discussionmentioning

confidence: 99%

Evaluation of continuous constant current and continuous pulsed current in sweat induction for cystic fibrosis diagnosis

et al. 2018

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BackgroundThe sweat test (ST) is the gold standard for the diagnosis of cystic fibrosis (CF). However, little is known about sweat induction using different types of currents and waves. In this context, our objective was to develop a device to induce sweat and compare the use of continuous constant current (CCC) and continuous pulsed current (CPC) in individuals with CF and healthy controls.MethodsA prospective cross-sectional study with experimental intervention. The variables of gender, ethnicity, age, and body mass index (BMI) were considered. The method of Gibson and Cooke was used, and the following markers were evaluated: sweat weight, electrical impedance, sufficient sweat amount, and CF diagnosis. Triangular (TPC) or sinusoidal (SPC) pulsed current was applied to the right arm, and CCC was applied to the left arm.ResultsThe study analyzed 260 individuals, 141/213 (54.2%) were female participants, 135/260 (51.9%) were Caucasians. The distribution of individuals by concentration of chloride at the ST was: (CF) 26/260 (10%); (borderlines) 109/260 (41.9%); (healthy) 97/260 (37.3%); (insufficient weight in sweat) 28/260 (10.8%). No association was observed between the sufficient sweat amount to perform the ST when we compared the currents. However, the SPC showed a higher amount of sweat weight. Using Bland and Altman plot considering the agreement between the sweat chloride values achieved from CPC [SPC and TPC] and CCC, there was no proportional bias and mean values are unrelated and only explain less than 8% of the variation. Moreover, TPC presented higher electrical impedance when compared with SPC and CCC. SPC presented lower electrical impedance and higher sweat weight than CCC. Male participants presented lower electrical impedance and higher sweat weight with CCC and TPC, and higher sweat weight with SPC.ConclusionsThe evaluated currents are safe and able to induce and produce sweat in sufficient quantities for the ST. SPC presented lower electrical impedance when compared with other currents. The use of SPC is recommended to induce sweat in patients with sweat problems. Finally, ethnicity, gender, age and BMI did not influence sweat induction at the ST, and no side effect was observed in our study.Electronic supplementary materialThe online version of this article (10.1186/s12890-018-0696-3) contains supplementary material, which is available to authorized users.

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Quality of sweat test (ST) based on the proportion of sweat sodium (Na) and sweat chloride (Cl) as diagnostic parameter of cystic fibrosis: are we on the right way?

Cited by 5 publications

References 24 publications

Thirty Years of Sweat Chloride Testing at One Referral Center

Thirty Years of Sweat Chloride Testing at One Referral Center

Sweat chloride quantification using capillary electrophoresis

Evaluation of continuous constant current and continuous pulsed current in sweat induction for cystic fibrosis diagnosis

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