4 doctors weighed in:

How typical are false positives on cystic fibrosis tests?

4 doctors weighed in
David Escobar
Family Medicine
2 doctors agree

In brief: Not Typical

Certain rare conditions can also lead to high sweat chloride levels (the gold standard test for cystic fibrosis).
However, these rare conditions (there's a list) will cause the patient to exhibit different symptoms than those consistent with cystic fibrosis, so the sweat chloride test is considered to be reliable in diagnosing CF in conjunction with the patient's history and physical exam.

In brief: Not Typical

Certain rare conditions can also lead to high sweat chloride levels (the gold standard test for cystic fibrosis).
However, these rare conditions (there's a list) will cause the patient to exhibit different symptoms than those consistent with cystic fibrosis, so the sweat chloride test is considered to be reliable in diagnosing CF in conjunction with the patient's history and physical exam.
David Escobar
David Escobar
Answer assisted by David Escobar, Medical Student
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Dr. Lokesh Guglani
Pediatrics - Pulmonology

In brief: Which CF test

Depends on the type of CF test you are referring to.
If it is newborn screening test (irt), then there are several conditions that can cause an elevated irt besides cf. For sweat chloride testing done by Pilocarpine iontophoresis, there are several rare conditions that can cause a false positive test. Please consult your local CF center or pediatric pulmonologist for more information.

In brief: Which CF test

Depends on the type of CF test you are referring to.
If it is newborn screening test (irt), then there are several conditions that can cause an elevated irt besides cf. For sweat chloride testing done by Pilocarpine iontophoresis, there are several rare conditions that can cause a false positive test. Please consult your local CF center or pediatric pulmonologist for more information.
Dr. Lokesh Guglani
Dr. Lokesh Guglani
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