The European Diagnostic Working Group presented comprehensive diagnostic algorithms for cystic fibrosis (CF) and confirmed the fundamental role of the sweat test for the diagnosis of CF.¹ However, several important differences between well-accepted guidelines for sweat testing^2,3 and the recommendations of the Working Group need to be discussed.

An adequate sweat sampling volume depends on the sampling area and not on the body surface area of the patient.^2,3 The unit therefore has to be cited as “g/m² sampling surface area/min sweat sampling time”^2,3 instead …