Sweat test

The sweat test measures the concentration of chloride that is excreted in sweat. It is used to screen for cystic fibrosis (CF). Due to defective chloride channels (CFTR), the concentration of chloride in sweat is elevated in individuals with CF. The sweat test measures the concentration of chloride that is excreted in sweat. It is used to screen for cystic fibrosis (CF). Due to defective chloride channels (CFTR), the concentration of chloride in sweat is elevated in individuals with CF. Cystic fibrosis is caused by defects in a protein found in many tissues, including the airways and the sweat glands. As a result, these tissues do not work properly. Sweat testing makes use of the fact that cystic fibrosis patients have defective sweat glands.