RT Journal Article SR Electronic T1 How to perform and interpret the sweat test JF Archives of disease in childhood - Education & practice edition JO Arch Dis Child Educ Pract Ed FD BMJ Publishing Group Ltd and Royal College of Paediatrics and Child Health SP 230 OP 235 DO 10.1136/archdischild-2018-316615 VO 105 IS 4 A1 Brown, Anthony A1 Jenkins, Laura A1 Reid, Alastair A1 Leavy, Anne A1 McDowell, Glen A1 McIlroy, Claire A1 Thompson, Andrew A1 McNaughten, Ben YR 2020 UL http://ep.bmj.com/content/105/4/230.abstract AB Cystic fibrosis (CF) is the most common life-threatening autosomal-recessive disease affecting Caucasians in the western world. The sweat test is the main diagnostic test for CF. It is indicated as part of the clinical assessment for infants that have picked up on the national neonatal screening programme. It may also be requested where clinical suspicion of a diagnosis of CF exists despite normal screening results. This article outlines the physiological basis behind sweat testing and the technical aspects of performing the test. Indications for performing the test are also considered. The article aims to provide clinicians with a guide to interpretation of results.