I know this doesn't sound like a doctor speaking.  But tell me, what's
the advantage of finding out if the baby has cystic fibrosis or not,
at this point when he is gaining well, and otherwise well?  The
downside is to worry the parents for no good reason.  In fact there is
more downside.  If the diagnosis is made and he lives in Toronto (and
probably not only here), the physicians will take the baby off the
breast and feed by bottle (so that they can measure the fat loss in
the stool).  Why do they want to measure fat loss?  What's so
important about measuring fat loss in the stool?  As a former chest
resident told me "you can't publish anything about cystic fibrosis if
you don't have that information".  AAAARGH!

I repeat the advice about the sunglasses, and would not suggest
anything about cystic fibrosis to the parents unless the baby was
failing to thrive or having repeated respiratory infections.

Babies with cystic fibrosis sometimes do very well on the breast
because of the lipase in the milk and the immune protective factors.

Jack Newman, MD, FRCPC