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Sweat chloride testing

Children’s – St. Paul

Monday-Friday Outpatient Lab
Phone: (651) 220-6565
Fax: (651) 268-2136

Children’s – Minneapolis

Monday-Friday Outpatient Lab
Phone: (612) 813-6280
Fax: (612) 813-6951

Your child has been scheduled for a sweat test at either the Children’s St. Paul or the Children’s - Minneapolis outpatient lab. When you come for the test, please bring your doctor’s orders with you, or ask your doctor to fax the order to Children’s ahead of time. This will help prevent delays or missed orders.

Registration

Your child must go to registration (also called “admitting”) before having a sweat test. When you register, you will be asked to provide information about your child, including:

your child’s name
the name of your child’s physician and ordering physician, if they are different
the name of your insurance company and policy number (please bring your insurance card with you)

Where to go

At Children’s - Minneapolis: Registration is on first floor near the main entrance. The lab is located on the lower level of the hospital. Please call the lab (612) 813-6280 to schedule an appointment.

At Children’s - St. Paul: Registration and lab are located on the 3rd floor of the Garden View Medical Building, 347 N. Smith Avenue, St. Paul, next to Children’s –

St. Paul. Weekday hours for performing sweat testing are Monday - Friday, from 8:30 a.m. to 1:30 p.m.

Please note that sweat testing is not performed on weekends or holidays.

Parking

Parking is available in the ramps on both campuses. Rates are posted at the ramp entrances; it is approximately $1.75 per hour.

Sweat testing: an overview

(information from the Web site of the Cystic Fibrosis Foundation)

The sweat test has been the “gold standard” for diagnosing cystic fibrosis (CF) for more than 40 years. When it is performed by trained technicians, and evaluated by an experienced, reliable laboratory, the sweat test is still the best test to diagnose CF. It is painless, relatively inexpensive, and gives definitive answers.

What happens during the test?

The sweat test is a simple, diagnostic procedure to determine the amount of chloride (salt) in the sweat. In the first part of the test, a colorless, odorless chemical gel disk known to cause sweating is applied to two small areas on the arm or leg. An electrode is then attached to stimulate a weak electrical current to the area. Individuals may feel a tingling sensation in the area, or a feeling of warmth. This part of the procedure lasts approximately five minutes.

The second part of the test consists of cleaning the stimulated area and collecting the sweat on a piece of filter paper or in a plastic coil “watch.” Thirty minutes later, the collected sweat is sent to the laboratory for analysis. The entire procedure takes approximately one hour.

What does the sweat test reveal?

Your child’s physician has asked for this test to rule out the presence of CF. Children and young adults with CF have an increased amount of chloride (salt) in their sweat. In individuals who have CF, the sweat chloride test will be abnormal from birth. Once a test result is positive, it is always positive. Sweat test values do not change from positive to negative as a person grows older. Test values also do not vary when individuals have colds or other temporary illnesses.

Is there any preparation for the test?

There are no restrictions on activity or diet or special preparations before the test. However, you should not apply creams or lotion to the skin 24 hours before the test. All regular medications may be continued and will have no effect on the test results. (Children’s recommends that your child be well hydrated and free of acute illness.)

When are test results made available?

The result of the sweat test is usually made available to your child’s physician on the next working day after the test is performed. In a small number of cases, the quantity of sweat obtained is not sufficient to give an accurate result (for instance, with some infants), and the test may need to be repeated. The results are available through your doctor -- please do not call Children’s lab.

Is the sweat test reliable?

In a small number of cases, the test results fall into “borderline” range between normal and abnormal. In these situations, repeat sweat tests, as well as other diagnostic procedures, may need to be carried out. These will only be done after consultation with a physician.