Paula --
IEP is an individual education plan, which is part of the special education laws or education benefit loaws. They allow for additional services and protections for diabled children not offered to other children such as accommodations, modifications, related and special ed service to allow the child to be successful in school.
Section 504 is a civil rights law that prohibits discrimination against individuals with disabilities. Section 504 ensures that a child with a disability has equal access to an education. The child may recieve accommodations and modifications even if he does not qualify for special ed. Any school or program receiving federal funds must follow this law.
In our district, a kid with CF or medical issues files a 504. And in it you and the school's administration decide what necessary accommodations are to be required. Once its in the 504 and agreed upon, they can't turn around and deny it. So you would want to include things like how he has to take his enzymes, that he needs better access to bathrooms, snacks in the afternoon, etc. I think it would be very important to find out what the school policy on absenteeism is. You should include in the 504 that if he misses more than X days of school in a row that they will provide a tutor for him in the hospital, or whatever works for you. I know most schools won't let a kid move to the next grade if they miss more than so many days, so you need to have this in the 504 that tutors count as school days.
We went to see Beth Suffian speak last spring. She's a lawyer with CF, who specializes in legal rights for those with CF. She talked a lot about the 504. You should contact your CF center social worker for additional ideas on how to handle this.
Hope this helps!!!