Our laboratory performs sweat testing according to the Cystic Fibrosis Foundation-approved manner. Testing for changes in the Cystic Fibrosis gene may also be ordered.
What happens during a sweat test?
The sweat test determines the amount of chloride (salt) in the sweat. In the first part of the test, a colorless, odorless chemical, known to cause sweating, is applied to a small area on an arm or leg. An electrode is then attached to the arm or leg in order to to apply a weak electrical current to the area to stimulate sweating. Patients may feel a tingling sensation in the area, or a feeling of warmth. This part of the procedure lasts approximately five minutes.
The second part of the test consists of cleaning the stimulated area and collecting the sweat on a piece of filter paper or gauze or in a plastic coil. Thirty minutes later, the collected sweat is sent to a hospital laboratory for analysis. The entire collection procedure takes approximately one hour.
What do you learn from the sweat test?
This test may be performed to rule out the presence of CF, an inherited disorder of the lungs, intestines and sweat glands. Elevated sweat chloride is seen in patients so if the test is positive the patient needs to be evaluated by a CF center.
Is there any special preparation for the sweat test?
There are no restrictions on activity or diet or any special preparations before the test. However, you should not apply creams or lotions to the skin 24 hours before the test. All regular medications may be continued. Patients should be well hydrated when the sweat test is done, so if the patient is acutely ill, the test is usually rescheduled.
For more information about sweat testing, visit the Cystic Fibrosis Foundation website.
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