Sweat test

Question

Good evening, we did a sweat test and they told us we were in the gray zone twice. They gave us a genetic test. The child doesn't have any clinical picture at all, respiratory problems, etc., only he is off the curve in height and weight a little above the red line. Please, because I'm about to go crazy. Could the borderline test be nothing? Could the genetic test be good?

Answer

Sweat test results:
Less than 30 mmol/L: Cystic fibrosis is unlikely
30 to 59 mmol/L: Cystic fibrosis is possible, further testing may be required (gray zone)
60 or more mmol/L: diagnostic for Cystic fibrosis
The sweat test value, in people without the disease, must be less than 30 mmol/L. Values ​​greater than 60 mmol/L are diagnostic for cystic fibrosis. Intermediate values ​​between 30 and 60 mmol/L are considered elevated but not diagnostic. Cystic fibrosis is possible in these patients, but repeat or alternative testing is necessary.
For patients with results in the gray zone (30 to 60 mmol/L), genetic testing can help confirm or rule out the diagnosis. In patients where two CF-causing variants on separate chromosomes are detected, no further diagnostic testing is required and the diagnosis of CF is confirmed. For patients where no CF-causing variants are detected, provided that complete genetic testing has been performed, no further testing is indicated as CF is unlikely. In patients were only one CFTR variant or CFTR variants with varying clinical consequences are detected, provided that complete genetic testing has been performed, the clinician should continue further testing and monitoring if clinical features of the disease are present.
Best regards,
M. Poulou

09.03.2025