Why do I need a sweat test?
A sweat test can diagnose cystic fibrosis (CF) in people of all ages, but it's usually done on babies. Your baby may need a sweat test if he or she tested positive for CF on a routine newborn blood test. In the United States, new babies are usually tested for a variety of conditions including CF. Most sweat tests are done when babies are 2 to 4 weeks old.
An older child or adult who has never been tested for CF may need a cystic fibrosis sweat test if someone in the family has the disease and/or has symptoms of CF. These include:
Salty-tasting skin
Frequent coughing
Frequent lung infections, such as pneumonia and bronchitis
Trouble breathing
Failure to gain weight, even with a good appetite
Greasy, bulky stools
In newborns, no stools made right after birth
