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Sweat Analysis

Why is my child having a sweat test?

Your health care provider asked that the sweat test be done to rule out Cystic Fibrosis (CF). CF is a genetic disease that causes mucus to build up and block some of the organs in the body, mainly the lungs and pancreas.

People with CF have more salt in their sweat than those who do not have CF. If someone has CF, the sweat test results will be positive soon after birth. A baby has to sweat enough to do the test. For full-term babies, this is usually by 2 weeks of age.

How do I get my child ready for the sweat test?

  • Babies should be at least 48 hours old.
  • There is no activity limit or special diet needed before the sweat test. Babies should be fed their normal amount at their normal times.
  • Patients should be well hydrated. Patients with an upset water balance will rarely sweat enough for the sweat test results to be accurate.
  • All regular medications may be continued. These will have no effect on the test results.
  • No creams or lotions should be applied to the skin 24 hours before the test.
  • Sick patients should not be tested, unless absolutely necessary. Testing sick patients may give wrong results. The test should then be done again after the patient is well.

When will I know the results of the sweat test?

CentraCare Laboratory Services provides sweat analysis for screening purposes only. The nursing staff or health care provider will discuss the sweat test results with the parent(s) or guardian(s) shortly after the test is done.

Reference range for sweat test results:
(For patients 48 hours old up to 16 years old)
Normal = 0 to 60 mmol/L
Equivocal = 61 to 80 mmol/L Possible CF = above 80 mmol/L

Can the test results be uncertain?

In a small number of cases, the sweat test results fall into the “equivocal” range. This means the results are between not having CF and having CF. When this happens the sweat test is usually done again.

In a small number of cases, the amount of sweat collected is not enough for an accurate result. When this happens the health care provider may have the test done again after 2 weeks. Your health care provider will discuss follow-up confirmatory testing or treatment plans with you.

Testing Sites

Inpatient Testing Site
1406 Sixth Avenue North, St. Cloud, MN 56303
(320) 255-5999 or (320) 251-2700, ext. 57320
Sweat analysis appointment times: 10 a.m. and 1 p.m. Monday-Friday

Outpatient Testing Site
1900 CentraCare Circle, St. Cloud, MN 56303
(320) 252-2422 or (320) 229-5199, ext. 74903
Sweat analysis appointment times: Noon-3 p.m. Monday-Friday

Questions? Call (320) 255-5999.


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