Sweat electrolytes is a test that measures the level of chloride in sweat.

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.