Sweat testing for cystic fibrosis: standards of performance in Australasia

Background: Accurate measurement of sweat chloride concentration is essential for the diagnosis of cystic fibrosis (CF). We surveyed all laboratories enrolled in the Royal College of Pathologists of Australasia Quality Assurance Program (QAP) for Sweat Electrolytes to determine how closely they comply with the Australian Guidelines for the performance of the sweat test for the diagnosis of CF. Methods: A detailed questionnaire covering most aspects of sweat collection and analysis was sent to all participating laboratories in 2007. Results: Twenty out of 38 laboratories completed the questionnaire. While adherence to accepted guidelines was noted in many areas, the following main variations were recorded: some laboratories were not doing enough sweat tests to maintain expertise; some were not collecting sweat for the recommended collection time; sweat conductivity was the only test available in some laboratories; there was a lack of agreement between the sweat chloride concentration used to indicate CF or define an equivocal result. Conclusions: There is room for improvement in the performance of the sweat test in some laboratories in Australasia. The Sweat Testing Working Party of the Australasian Association of Clinical Biochemists is the appropriate body to address the problems involved in sweat testing and to bring about change.