Tests & Procedures



Diagnosis of Cystic Fibrosis

How is cystic fibrosis diagnosed?

In addition to a complete medical history and physical examination, diagnostic procedures for cystic fibrosis may include the following:

  • Sweat (chloride) test. A test to measure the amount of chloride in the sweat. The test is performed 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 your child. The sweat is collected onto a gauze pad and analyzed. Higher than normal amounts of chloride may suggest cystic fibrosis. The sweat test is not painful and usually causes minor discomfort.
  • Genetic tests. Blood or cheek scraping cells can be tested for mutations in the CFTR gene.
  • Blood tests. Blood tests, including pancreatic function tests, can assess infection, and involvement of certain organs.
  • Chest X-rays. A diagnostic test which 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 performed with special machines that a child must breathe into.
  • Sputum cultures. A diagnostic test performed on the material that is coughed up from the lungs and into the mouth. A sputum culture is often performed to determine if an infection is present.
  • Stool evaluations. These are done to measure stool fat absorption.

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Online Resources of Respiratory Disorders

Last reviewed: 7/4/2012