Sweat Test: What To Think About

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What To Think About

• Usually, two sweat tests are done to confirm a diagnosis of cystic fibrosis.
• Younger babies may not produce enough sweat to give reliable test results and may have lower sweat chloride levels than older babies and children with cystic fibrosis.
• A sweat test cannot identify carriers of the cystic fibrosis gene. If your child is diagnosed with cystic fibrosis, you may wish to talk with your health professional about genetic counseling. For more information, see the topic Cystic Fibrosis Carrier Screening.
• Adults generally have higher salt concentrations in their sweat than children. Also, sweat test results in adults can vary widely. This is especially true in women, because the amount of salt in their sweat can vary with the phase of their menstrual cycle. Enough sweat must be collected to get accurate test results.
• If results of a sweat test are positive or unclear (especially in babies), a blood test may be done to detect changes in the genetic material (DNA) that causes cystic fibrosis. Blood test results are usually ready in 10 to 21 days. For more information, see the medical test Genetic Test.
• Sweat tests should be done at labs that are certified by the Cystic Fibrosis Foundation. These labs perform a large number of sweat tests and are skilled at sweat test techniques and interpretation.

Last updated:	June 26, 2007
Author:	Debby Golonka, MPH
Reviewed By:	Michael J. Sexton, MD - Pediatrics, Susanna McColley, MD - Pediatric Pulmonology
Editors:	Susan Van Houten, RN, BSN, MBA, Tracy Landauer