The original diagnostic test for cystic fibrosis is called a sweat test. The test induces sweating using electrical stimulation and then collects that sweat to see how salty it is. At the cellular level, the main defect of CF is that the chloride channels in the cells of the body do not work properly.
People with CF have extremely salty skin and have to eat extra salt to replace all that they lose. Matt had actually noticed that Lucie's skin was salty when he kissed her as a newborn…even before we knew she had CF!
Our kids have had a lot of sweat tests, from Lucie's first one at 12 days old to recently having one every few months during her first year in a Trikafta clinical trial!
To learn more on the sweat test for CF, read this from the Cystic Fibrosis Foundation.