How reliable is a negative sweat chloride at ruling out CF in someone?

See below. The sweat chloride test is the gold standard for diagnosing cf. If an adequate amount of sweat was obtained, and the test was negative, then CF is unlikely.
Repeat if suspected. The sweat chloride test is reliable in ruling out CF, but if there are symptoms, I would suggest a repeat sweat chloride test and genetic testing.

Related Questions

How reliable is a sweat chloride test in ruling out cf?

Cystic fibrosis. The sweat test is usually done when the infant is a month old, to ensure the sample is large enough to be analyzed. The sweat test can determine if the infant carries the cystic fibrosis gene or has the condition. Testing should be done at a center specializing in cystic fibrosis. Read more...
If symptoms rep test. If the sample collection and test is performed correctly it is very reliable. If a patient is experiencing symptoms that raise a suspicion for cf, the test should be repeated and a genotype analysis ordered. Read more...