Health Encyclopedia

Diagnosis of Cystic Fibrosis

How is cystic fibrosis diagnosed?

In addition to a complete medical history and physical exam, diagnostic procedures for cystic fibrosis (CF) may include:

  • Sweat (chloride) test. A test to measure the amount of chloride in the sweat. The test is done by placing a solution on the forearm (or the thigh, if the child is too small) and attaching electrodes. The skin is stimulated to sweat with a mild electric current, which does not cause pain or harm to your child. The sweat is collected onto a gauze pad and analyzed. Higher than normal amounts of chloride may suggest CF. The sweat test is not painful and usually causes only minor discomfort.

  • Genetic tests. Blood or cells taken from a cheek scraping can be tested for mutations in the CFTR gene. 

As part of the doctor's assessment of CF symptoms, your child may also have these diagnostic procedures:

  • Blood tests. Blood tests, including pancreatic function tests, can look at infection and to see which organs may be affected. 

  • Chest X-rays. A diagnostic test that uses invisible electromagnetic energy beams to produce images of internal tissues, bones, and organs onto film.

  • Pulmonary function tests. Diagnostic tests that help to measure the lungs' ability to exchange oxygen and carbon dioxide appropriately. The tests are usually done with special machines that a child must breathe into.

  • Sputum cultures. A diagnostic test done on the material that is coughed up from the lungs and into the mouth. A sputum culture is often done to find out if an infection is present.

  • Stool evaluations. These are done to measure stool fat absorption.

 



Medical Reviewers:

  • Bass, Pat F. III, MD, MPH
  • Kidd, India, RN, BSN, MBA