What happens if individuals who are suffering from celiac disease don't respond to gluten free diet?

Recheck diagnosis: If a person with celiac disease does not get well on a gluten-free diet, his doctors can re-evaluate to see if he truly has celiac disease, if his diet is really completely gluten-free, or if he has a second problem causing the symptoms that were believed to be caused by celiac disease.

Avoid casein too: Must also avoid casein. There is cross reactivity. Could also be other food sensitivities. Also prescription meds can contain gluten.