Iranian Journal of Pediatrics
Tehran University of Medical Sciences Press
Vol. 22, No. 1, 2012, pp. 102-106
Bioline Code: pe12017
Full paper language: English
Document type: Research Article
Document available free of charge
Iranian Journal of Pediatrics, Vol. 22, No. 1, 2012, pp. 102-106
© Copyright 2012 - Iran Journal of Pediatrics
Comparison of Classic Sweat Test and Crystallization Test in Diagnosis of Cystic Fibrosis|
Farahmand, Fatemeh; Sadjadei, Nooshin; Haghi-Ashtiani, Mohammad-Taghi; Modaresi, Vajiheh; Rezaei, Nima & Pakseresht, Bahar
Objective: Sweat chloride measurement is considered a standard diagnostic tool for cystic fibrosis (CF). This
study was performed to compare sweat chloride values obtained by quantitative pilocarpine iontophoresis
(classic test) with sweat crystallization detected by direct observation of a drop of perspiration under light
microscopy in patients with and without CF.
Methods: The tests using both techniques were performed simultaneously in patients with and without CF.
Cutoff values of ≥60 mmol/L of chloride concentration for the classic sweat test was considered for diagnosis
of CF. In crystallization method, observation of typical dendritic forms of salt crystals under light microscopy
was interpreted positive.
Findings: Sixty patients suspected to CF (31 males and 29 females) with age range of 9 months to 2 years
underwent the sweat test using both techniques. Median sweat chloride values was 26.13+10.85 in group
with negative and 72.76+12.78 mmol/L in group with positive sweat test, respectively. All the patients who
had positive sweat test in classic method showed typical dendritic forms of salt crystal in sweat crystallization
test, which provided the test with 100% sensitivity (95%CI: 93.1-100). Only one of the 31 subjects with
negative results for classic sweat test had positive result for crystallization sweat test, which provided the test
with 96.7% specificity (95%CI: 92.9-100). Time spent to perform the crystallization test was significantly
shorter than the classic method whereas its cost was also lower than the second method.
Conclusion: There was a good correspondence between two studied methods of sweat test. These results
suggested the sweat crystallization test as an alternative test for detecting CF disease with high sensitivity and
Cystic fibrosis; Diagnosis; Sweat chloride; Sweat crystallization
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