Not to insult your pedi. but many of them have been grossly incorrect at the expense of a childs health simply because they don't understand CF, they are too prideful to admit it isn't their array of knowledge... and so on.
Here's where I would start, since your endo. seems to think your son might have classic CF symptoms, request that they order a blood test via quest diagnostics. Quest Diagnostics is a well known, well respected, long standing laboratory and is very well known to many doctors and insurance companies. Here are some links to the CF test there, print print print and give to your doctor (contrary to popular belief, doctors don't know everything and are FREQUENTLY wrong!)<a target=new class=ftalternatingbarlinklarge href="http://www.questdiagnostics.com/hcp/topics/cfcomplete/cfcomplete.html">http://www.questdiagnostics.com/hcp/topics/cfcomplete/cfcomplete.html</a>,
<a target=new class=ftalternatingbarlinklarge href="http://www.questdiagnostics.com/hcp/topics/cf/cf.html">http://www.questdiagnostics.com/hcp/topics/cf/cf.html</a>,
If the insurance company denies the testing, appeal it, if they deny it again, appeal it again. People are still so ignorant about CF, even in the medical field. You have to fight, believe me, you have to fight.