child not gain weight?

I have a friend who's 2 year old is not thriving at weight and recently had bloodwork done and they told her it could be cystic fibrosis. My question is ..is cystic fibrosis the only possible answer to a child's rufusal of weight gain?

[Renee Radenberg]

Cystic fibrosis (CF) does cause a child not to gain weight and they may not have any other symptoms at this age. I recommend her MD do a "sweat" test on the child to correctly diagnosis CF or not. There are other diseases that cause weight loss, however, there would be other problems besides weight loss. Hope this helped.