Testing & Diagnosis for Cystic Fibrosis in Children

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Contact the Cystic Fibrosis Center

The first step in treating your child is forming an accurate and complete diagnosis. All newborns in Massachusetts — and most other states — are screened for cystic fibrosis. If doctors suspect that your child has CF, they will want to perform a sweat test.

This is to make an area of your child’s skin sweat enough so that doctors can collect some sweat and determine how much salt (sodium and chloride) is in it. A high level indicates CF. The test takes about 40-45 minutes from start to finish. We perform about 1,250 of these tests each year.

What happens during the test?

1. Preparation

We start by putting two gauze pads on each if your child’s forearm (or thigh, if your child is very young). The pad closest to the wrist has a mild chemical in it and is used to stimulate or activate the sweat glands. It feels like water.

2. Stimulation

We then attach electrodes to the pads and run a small current through them. This part of the test lasts 5 to 10 minutes and may not cause any sensation, or your child may sense a mild tingling. The test doesn’t hurt.

3. Collection

After 5 to 10 minutes, we wipe the sites with water, dry your child’s arms and put pre-weighed gauze on the sites that were stimulated. The gauze is then covered with plastic wrap, secured with tape, and left in place for 25 minutes. During this time, your child can sit in the hallway or go for a walk and is allowed to eat.

4. Analysis

After the waiting period, the gauze pads are removed and analyzed for salt content. Although the results are not ready immediately, we call them into your primary care physician's office on the day of the test.

Your child’s doctor may also order one or more of the following:

  • blood tests - we can test your child’s blood cells for mutations in the CFTR gene. Other blood tests can assess infection and tell us whether other organs may be involved.
     
  • chest x-rays
     
  • pulmonary function tests to measure the lungs' performance. In these tests, your child will simply breathe into one or more special machines.
     
  • sputum cultures - a sputum culture (performed on the material that is coughed up from the lungs and into the mouth) is often done to test for infection.
     
  • stool evaluations to measure stool fat absorption
     
  • pancreatic function tests to assess the pancreas

After we complete all necessary tests, our experts meet to review and discuss what they have learned about your child's condition. Then we’ll meet with you and your family to discuss the results and outline the best treatment options.

We are grateful to have been ranked #1 on U.S. News & World Report's list of the best children's hospitals in the nation for the third year in a row, an honor we could not have achieved without the patients and families who inspire us to do our very best for them. Thanks to you, Boston Children's is a place where we can write the greatest children's stories ever told.”
- Sandra L. Fenwick, President and CEO

Boston Children's Hospital 300 Longwood Avenue, Boston, MA 02115 617-355-6000 | 800-355-7944

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