Cystic fibrosis, CF, is a genetic disease of the exocrine glands (Cystic Fibrosis) that affects approximately thirty thousand children and adults in the United States (Facts About CF). The median survival is twenty five years in females and thirty years in males (Cystic Fibrosis) Some symptoms of CF include a distended abdomen, diarrhea, foul-smelling stools, malnutrition even though a healthy diet is instituted, nasal polyps, sinus disease, repeated respiratory disease, infertility, liver disease and diabetes (Cystic Fibrosis). The symptoms of CF are caused by the genetic abnormality in the transmembrane conductance regulator gene that causes the disruption of chloride transfer across cell membranes. Because of this, chloride ions build up inside the cells of the lungs and other organs. Water remains inside the cells to dilute this excess rather than being drawn out of the cell by normal chloride movement, so the normal secretions of the organs thicken. Eventually, mucus is so thick that it blocks the ducts of the exocrine glands and forms cysts, especially in the pancreas, lungs, and liver.

The disease also causes excessive salt to be excreted by the sweat glands, causing heat prostration in winter (Cystic Fibrosis). Therefore, the sweat test is the test used most often to diagnose the disease (Facts About CF). The sweat test is a simple diagnostic test that has been used to diagnose cystic fibrosis for the past forty years. When it is performed by trained technicians in a reliable laboratory, it is the best method to diagnose CF. The actual test is painless and relatively inexpensive. It can be performed on people of all ages, but some young babies may not produce enough sweat to test, in that case the test should be repeated..