Sweat Test Results Please help me understand

[susied]

My daughter (age 9) had a sweat test yesterday due to large nasal polyps and severe "allergies" and wheezing in her right lung. History of allergies that no medication as helped, etc. Her results were 53/10. I was able to get the results from a woman in the lab at John Hopkins but she was not able to interpet them for me because she is not my daughter's ENT and didn't have her background health information.

Her ENT- who ordered the test- is not in the office today so I have to wait until tomorrow. I have read that 40-59 results are "borderline." Anyone else have a 53 as a sweat test result? I know her ENT will call tomorrow but I'm being impatient and am worried about the unclear "borderline" results. Thank you from a mom who is trying to figure out my daughter's health. It's so sad to watch my child be sick all the time. Blessings, Susan

 

[SarahProcter]

You need full genetic sequencing done, sorry.

My kid, who definitely has CF, had sweat tests in the 50s and indeed in the 40s and below when younger. A 53 means you should get a full genetic sequencing test done (not a panel!) and you should go consult with a certified CF center, not just an ENT.

 

[anindita79]

My son also had sweat test result as 53..He was retested and came up with 63...here they almost always do a 2nd sweat test in such cases...normally anything below 60 is considered as atypical CF.Then also genetic testing should be done to check mutations

 

[Julie78]

Hey there. I wanted to let you know that the testing guidelines changed a couple years ago (and cff adopted in 2017), but I keep seeing people post that under 40 is negative, but it is not, it is inconclusive/indeterminate for all ages. 29 and under is Negative. 30 -59 is inconclusive and is more common with other variants. Just wanted to pipe in after my new pulm looked at my old records after I told him I was "negative" and was not. I'm waiting on new sweat test results, but either way, I wanted to share that info!

ETA: Check this link out, scroll to "new issues"

https://www.cff.org/Care/Clinical-C...idelines/Sweat-Test-Clinical-Care-Guidelines/

New Issues
Normal sweat chloride concentration is 29 mmol/L or less (Farrell 2017).

Intermediate sweat chloride concentration is 30-59 mmol/L (Farrell 2017). Intermediate sweat chloride values have been documented in genetically proven cystic fibrosis.

Newborns with a positive CF newborn screen should have the test performed bilaterally when the infant weighs more than 2 kilograms (kg), and is at least 36 weeks of corrected gestational age. These measures increase the likelihood of collecting an adequate sweat specimen (Farrell 2017).

Newborns greater than 36 weeks' gestation and more than 2 kg body weight who have a positive CF newborn screen or a positive prenatal genetic test should have sweat chloride testing performed as soon as possible after 10 days old, ideally by the end of the neonatal period (Farrell 2017).

For infants with presumptive CF identified through NBS, CF treatment should not be delayed while efforts to establish a diagnosis of CF are initiated (Farrell 2017).

Sweat chloride analysis should be performed within a few hours of sweat collection, and the results and interpretations should be reported to clinicians and parents or patients as soon as possible and certainly on the same day (Farrell 2017).

Patients who have intermediate sweat chloride concentrations should have repeat tests within 1-2 months. Genetic testing should be offered. Ancillary tests, such as stool elastase, should be considered (Ren 2017).