The sweat test

Diagnosing cystic fibrosis with the sweat test 💦

For some babies and their families the sweat test is very important as the diagnosis is not 100% certain from the blood tests but for Arlo we were told right away that he had two copies of the DF508 mutation (homozygous) and that there was no way he did not have CF so the sweat test was more of a formality that the team had to complete. It also gives them a number that correlates to the level of fluoride in Arlo’s sweat - anything over 60 is a CF diagnosis and Arlo’s was 80. CF babies have much higher salt content in their sweat - when I kiss his little forehead I can literally taste it bless him!

The test itself involves strapping little pads to his arm with a substance on them called Pilocarpine, in order to make him sweat they also need to stimulate the skin with a small battery which they told us would tingle but not hurt, and then they collect a few droplets of his sweat in a little vial on his skin.

Sadly for Arlo, he was too tiny and as newborns do not sweat much, he did not sweat enough to get a result. But we did re-do the test about 2 months later when it worked! Little trooper!

This is a photo of his feeding and then sleeping through the test - what a legend!!

Diagnosing