Sweat Test for Cystic Fibrosis Test
A sweat test measures the amount of chloride in your sweat to help diagnose cystic fibrosis (CF).
What this test measures
A sweat test measures the amount of chloride in your sweat. Chloride is an electrolyte that helps control fluid and acid-base balance in your body.
What your results mean
Reference ranges vary by laboratory and by your age and sex. MedlinePlus does not publish a single normal range for this test — always read your result against the range printed on your own lab report and discuss it with your provider.
Higher-than-normal results
A chloride level of 60 or greater means that you or your child most likely has cystic fibrosis.
Lower-than-normal results
A chloride level less than 29 is normal. This means that you or your child is unlikely to have CF. But a normal test result doesn't rule out CF.
Frequently asked questions
What does a sweat test measure?
It measures the amount of chloride in your sweat.
What does a high chloride level mean?
A chloride level of 60 or greater means you most likely have cystic fibrosis.
What does a borderline result mean?
A chloride level between 30 and 59 means more testing is needed because the result is unclear.
Can a normal sweat test rule out CF?
No, a normal result (less than 29) means CF is unlikely, but it doesn't rule it out completely.
What is cystic fibrosis?
CF is an inherited disease that causes thick, sticky mucus, leading to lung infections and organ damage.
Related lab tests
Sources
- MedlinePlus: Sweat Test for Cystic Fibrosis — NIH MedlinePlus
Last updated . Information is aggregated from official public sources and is not a substitute for professional medical care.