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Sweat Chloride Test

What is a Sweat Chloride Test?

A sweat chloride test, also called a sweat test, is done to find out if a child has cystic fibrosis (CF).

Your child is having this test done because of symptoms that are sometimes seen in children who have cystic fibrosis.

About Cystic Fibrosis

Cystic fibrosis is a chronic condition in children and adults. About one out of every 3,000 people has CF. It most often affects the lungs and digestive system. Children with CF may have chronic lung infections or problems digesting their food.

Signs and Symptoms of CF

It is important to know that many children have some of these symptoms but they do not have CF.

  • Chronic cough
  • Frequent lung infections
  • Poor weight gain
  • Nasal polyps
  • Wheezing
  • Salty skin
  • Frequent, bulky bowel movements

Description of the Test

The sweat test is a simple test that takes about one hour. It is done by placing a solution on the forearm and stimulating the skin to sweat with a small electrical current. The sweat is then collected on a small piece of gauze.

Your child may feel a tingling in the arm, but this test is not painful.

Preparing Your Child for the Test

  • Make sure that your child drinks lots of fluids the night before the test.
  • Bring a jacket, sweater, or blanket for your child to wear during the test.
  • Do not use soap or lotion on your child's arms on the morning of the test.
  • If your child is a baby, you may offer them a bottle while the sweat is being collected.

Additional Information

Sweat test results are available late in the afternoon on the day of the test. To get results, contact the ordering doctor/practitioner.

Your child should not be on iodide or bromide. It interferes with the sweat chloride test. This does not include the iodide in vitamins or salt.

For more information about CF, go to the Cystic Fibrosis Foundation website or contact the CF Center at Cincinnati Children's, 513-636-6771.

Last Updated 10/2023

Reviewed By Jayne Massengale, RN