Would someone please help me with this doubt...

With my 3-year-old son, I ended up at the pediatrician because of his low weight (13kg/99cm).

There I expressed my concern about the possibility of CF, because of some symptoms (meconium only after 48 hours after enema, somewhat longer jaundice after birth, often coughs for periods after colds, bulky, fatty stools that float and of course the weight which is lagging behind).

The doctor did not fully agree with my idea about this, but I insisted on having elastase tested and a sweat test.

Elastase was 405 and the sweat test negative (15cl / 18na).

Only ... now I know that elastase is usually >500 and that sweat tests can sometimes be false negative. My doctor, however, called me with the message that CF is now 100% excluded.

I have a hard time letting this go because of the symptoms. I notice that DNA testing is being used with caution. Am I entitled to this in view of the doubts I otherwise hold?

How do you read the results of the 2 tests in relation to the symptoms?