Cystic Fibrosis - Diagnosis - Diagnosis

To diagnose cystic fibrosis, your doctor may recommend some of the following tests and procedures:

• Genetic testing to detect mutated CFTR genes. This test can confirm a positive cystic fibrosis screening test and sweat test. If genetic testing is done as part of newborn or other screening, it may not be repeated during the newborn stage. Genetic testing is described in more detail in Screening and Prevention.
• Prenatal diagnostic tests to diagnose cystic fibrosis in an unborn baby, using mutated CFTR genes. This is done with procedures that take either a sample of amniotic fluid, the liquid in the sac surrounding your unborn baby, or tissue from the placenta . Cells from these samples are checked for gene mutations. Infants with positive prenatal testing for cystic fibrosis will be further tested after birth to confirm the diagnosis of cystic fibrosis.
• Sweat test for high sweat chloride to see if you have high levels of chloride in your sweat. The sweat test is the standard test for diagnosing cystic fibrosis. It may be used if you have symptoms that may indicate cystic fibrosis, or to confirm a positive diagnosis from a screening of your newborn baby. A normal sweat chloride test alone does not mean you do not have cystic fibrosis. Lower levels of chloride may indicate the need for further testing to diagnose or rule out cystic fibrosis.

How is a sweat chloride test performed?

• Return to Risk Factors to review family history and racial or ethnic factors that increase your risk of developing cystic fibrosis.
• Return to Signs, Symptoms, and Complications to review common signs and symptoms of cystic fibrosis.
• Return to Screening and Prevention to review how to screen for cystic fibrosis.