Sweat Chloride Test

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A sweat chloride test is done to find out how much chloride is in your child’s sweat. Too much chloride in the sweat is one sign of some diseases. The results of the test will help your child’s doctor find out what is causing your child’s problem.

How to Prepare for the Test

  • If your child is old enough, explain the test.

  • Bring a sweatshirt, coat, or a heavy blanket to keep your child warm during the test so he or she will sweat.

  • Bring something to keep your child entertained while the test is being done (books, toys, or games).

  • Change your child’s diaper, if needed, before the test so he or she can stay bundled.

  • Be prepared to stay about 2 hours.

How the Test is Done

  1. A lab technician will choose an area on the child’s arm or leg for the test. This area will be cleaned with alcohol pads, then with deionized water, and then dried with gauze.
  2. Two electrodes containing two small gel disks are applied to the area and held in place with Velcro® straps.
  3. A machine that gives off a small amount of electricity is attached to the electrodes. When the electrodes stimulate the skin it will cause your child’s skin to sweat. There may be a slight pricking feeling at this time. This is normal. However, if it gets uncomfortable for your child, tell the technician. This part of the test takes about 5 minutes.
  4. The electrodes and machine are then removed and the arm or leg is washed again with deionized water.
  5. A disk containing a clear spiral tube to collect sweat is put exactly where one of the electrodes was, and held in place by the Velcro® strap. Plastic wrap or tape may be used to help hold the disk in place.

  6. Steps 1-5 will be done again on the other arm or leg.

  7. After the second collector disk is in place, you and your child will go back to the waiting room. Please keep the child covered and warm while the test is going on. Your child may move around quietly, but try to keep him or her calm so that the collectors remain in place on the arms. Your child must stay warm during the collection time.

  8. Do not leave the waiting room. If the child is not there when the collector needs to be taken off, the test will need to be redone.

  9. The tube containing the sweat is taken off. The sweat is put in a small test tube.

  10. The Velcro® straps are undone and the disk is taken off.

  11. Steps 8 & 9 are repeated on the second collection site.


There is a rare chance that the electrodes may burn your child’s skin, or your child may have a reaction to the chemical used in the gel disks. If either of these things happens, tell your child’s doctor, nurse or lab technician right away.

During the Test

Your child must stay covered and warm for up to 30 minutes while the sweat collector is on. Quiet entertainment is allowed, but your child must remain covered. It will help if you plan quiet play by bringing a favorite book, game, or toy from home to occupy your child during the test.

After the Test

  • The tubes containing the sweat are sent to the lab. The results of the test will be sent to your child’s doctor.

  • If you have any questions, be sure to ask your child’s doctor or nurse.

  • This test needs to be scheduled with the most convenient Laboratory Service Center. Please call the phone number listed below. 

For directions to the nearest Laboratory Service Center, please call Laboratory Services at (800) 934-6575 or visit NationwideChildrens.org/Lab.

Sweat Chloride Test - Collection Guidelines (PDF)

HH-III-62 17/83 Revised 12/16 Copyright 1983 Nationwide Children’s Hospital