Chloride Sweat Test

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KEY POINTS

• The chloride sweat test measures the amount of a chemical called chloride in your sweat. This test is done to diagnose cystic fibrosis.
• A small amount of sweat is collected from your skin and sent to a lab.
• Talk to your healthcare provider about what the test results mean and ask any questions you have.

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What is the chloride sweat test?

This test measures the amount of chloride in your sweat. Chloride is one of several chemicals in the body called electrolytes. Electrolytes help control the amount of fluid in your body and the way your muscles, nerves, and organs work. You need the right balance of chloride and other electrolytes in your body to stay healthy. The balance of electrolytes in your body can be affected by food, medicines, drinking too much or too little water, or problems with your lungs, kidneys, and other organs.

Why is this test done?

This test is done to diagnose cystic fibrosis. Cystic fibrosis (CF) is a disease that causes the body to make thick, sticky mucus. The thick mucus blocks airways, damages the lungs, and makes it hard to breathe. People with CF have more chloride (salt) in their sweat than someone who does not have CF.

How do I prepare for this test?

Usually no preparation is needed for this test. Talk to your healthcare provider if you have any questions about the test.

How is the test done?

To do the sweat test, a small wire is put on the skin. A weak electrical current causes the area to sweat. The sweat is collected and tested in a lab. This test does not hurt.

Ask your healthcare provider when and how you will get the result of the test.

What does the test result mean?

A positive sweat chloride test means that it is likely that you have cystic fibrosis.

What if my test result is not normal?

Test results are only one part of a larger picture that takes into account your medical history, physical exam, and current health. Sometimes a test needs to be repeated to check the first result. Talk to your healthcare provider about the results and ask questions, such as:

• If you need more tests
• What kind of treatment you might need
• What lifestyle, diet, or other changes you might need to make