We also use "medical condition" rather than disease or other terms. For those who need more specifics, I say "adrenal gland condition".

Personally, I believe the choice of words is very, very important. When my 7 yr old was an infant, I was much more open with sharing information. It came back to haunt us several times. Luckily he was too young to suffer the negative consequences.

Please consider your choice carefully, it will affect how others treat your child, and eventually, how your child views him or herself.