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.
  • blood tests - blood or cheek scraping cells can be tested for mutations in the CFTR gene. Other blood tests can asses 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 - to measure stool fat absorption.
  • pancreatic function tests

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