Anne,
This may feel like your case is falling apart, but I do want to assure you
that it is well within your scope as a LLL Leader to contact the mother's
pediatrician and express any concerns you may feel. It might be helpful to
open by saying, "Mrs. X has called me a couple of times about her baby and a
problem with weight loss.  While she no longer desires my help, it appeared
to me from our last conversation that the baby's situation is deteriorating,
and since she doesn't plan to see you again until __, I wanted to make you
aware of this situation in case you might want to follow-up sooner, as I feel
that this baby has become FTT." And then, tell the MD the basic facts you
collected, what LLL's cut=off for acceptable weight loss is, and that you
therefore felt compelled to contact him with the details you collected on
this mom.

If there was a miscommunication on the MD's part, he will be grateful to get
a fuller picture. And if you somehow misunderstood the facts, you will be
reassured after this fact (hopefully).  IMO, you do have an obligation to let
the MD know of a possible dangerous health problem so that he can check it
out for himself.

-Lisa Marasco, BA, LLLL, IBCLC