Sweat electrolytes is a test that measures the level of chloride in sweat. Although genetic tests have become important methods for determining whether a child has cystic fibrosis, the sweat chloride test remains important.
Sweat test; Sweat chloride; Iontophoretic sweat test
In the first part of the test, a colorless, odorless chemical that causes sweating is applied to a small area on an arm or leg. An electrode is then attached to the arm or leg, which allows the technician to apply a weak electrical current to the area to stimulate sweating.
People may feel a tingling sensation in the area, or a feeling of warmth. This part of the procedure lasts approximately 5 minutes.
The next part of the test involves cleaning the stimulated area and collecting the sweat on a piece of filter paper or gauze, or in a plastic coil. After 30 minutes, the collected sweat is sent to a hospital laboratory for analysis. The entire collection procedure takes about 1 hour.
No special preparation is necessary. Make sure the center where the test is being performed is a cystic fibrosis testing center.
Though the test is not painful, some people describe a tingling sensation at the site of the electrode. In smaller children or infants, the sensation can cause irritability or discomfort.
Sweat testing is the standard method for diagnosing cystic fibrosis. People with cystic fibrosis have higher amounts of sodium and chloride in their sweat, which the test can detect.
Some people are referred for testing because of symptoms such as poor growth, many respiratory infections, or foul-smelling stools. In some states, newborn screening programs test for cystic fibrosis, and the sweat test is used to confirm these results.
Note: mEq/L = milliequivalent per liter
Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.
An abnormal test may indicate the presence of cystic fibrosis.
Boat TF, Acton JD. Cystic fibrosis. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF, eds. Nelson Textbook of Pediatrics. 18th ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 400.
Farrell PM, Rosenstein BJ, White TB, et al. Guidelines for diagnosis of cystic fibrosis in newborns through older adults: Cystic fibrosis consensus report. Journal of Pediatrics. Aug 2008;153(2).
Review Date: 5/27/2009
The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. Copyright ©2010 A.D.A.M., Inc., as modified by University of California San Francisco. Any duplication or distribution of the information contained herein is strictly prohibited.
Information developed by A.D.A.M., Inc. regarding tests and test results may not directly correspond with information provided by UCSF Medical Center. Please discuss with your doctor any questions or concerns you may have.