If other likely alternatives have been ruled out, I would pursue a genetic test. I have two daughters with CF. One with sweat chloride of 11 and the other 49. They are part of the "new" class of diagnoses that are resulting from a better understanding of the genetics. They have only one Delta 508 5T each, so they would normally be considered carriers. However, they have a combination of other mutations are known to lead to partial expressions of CF that range from mild to full-blown. They both have the same genetic markers, but one tested borderline (49) and the other low (11). Both have benefited significantly from CF care and are sick less often now. Interestingly, it is the low scorer who has the most trouble maintaining her weight. She passes all the digestive panels, but she is very tiny and we struggle to keep her BMI up where the doctors want it.
The only reason they were diagnosed was that we have a very proactive pediatrician who insisted they both get genetic tests, even though only one had a questionable result.
The only reason they were diagnosed was that we have a very proactive pediatrician who insisted they both get genetic tests, even though only one had a questionable result.