Cystic Fibrosis: When Your Child Needs a Sweat Test
A sweat test confirms whether or not your child has cystic fibrosis. A sweat test is an easy, simple, and accurate test. It is safe for a child of any age. Its purpose is to make the skin sweat enough to collect salt. A high level of salt in the sweat is common in people with cystic fibrosis.
Before the test
Give your child any regular medicines as usual. They won’t affect test results.
Avoid using lotion or soap on your child’s arms or legs for
24hours before the test.
Bring something to help your child stay warm during the test. You can bring a blanket, sweater, or jacket.
During the test
This is a painless test that uses no needles. It takes about 60 minutes to complete. Here’s what you can expect:
A technician applies an odorless, colorless chemical to a small area on your child’s arm or leg.
The technician then attaches an electrode to this area. The electrode produces a weak electrical current. This causes sweating. It is painless, but may cause mild tingling or warmth. The electrode remains in place for about 5 minutes.
The technician removes the electrode, then cleans and dries the area.
Next, the technician applies filter paper, gauze, or a plastic coil to your child’s skin. This collects sweat for about 30 minutes. During this time, your child can move around, eat, play, or relax.
The collection device is removed and sent to a lab for analysis.
After the test
You and your child can go home after the test. Your child’s doctor will receive the test result within a day or two. In rare cases, a child doesn’t produce enough sweat or the test is not clear. The test can be repeated. Or, your child can have other tests to confirm a diagnosis.