Most children are now diagnosed with CF at birth through newborn screening, and more than 75 percent are diagnosed by the age of 2. A doctor who sees the symptoms of CF will order a sweat test and/or a genetic test to confirm the diagnosis.

  • A sweat test measures the amount of salt in a person's sweat. A mild chemical and a small amount of electricity are placed on the skin (usually on the arm) to stimulate the sweat glands. Sweat is then collected and the amount of chloride, a component of salt in the sweat, is measured. A high level of chloride means that the person has cystic fibrosis. The sweat test is painless.
  • In a genetic test, a blood sample or cells from the inside of the cheek are taken and sent to a laboratory that specializes in genetic testing. A genetic test is often used to confirm a diagnosis of CF if the results of a sweat test are not clear, but genetic testing is mostly used to find out if a person is a CF carrier.
  • Newborn screening is available. Learn more here.