Celiac Disease symptoms are usually classified as gastrointestinal, extra-intestinal, or associated conditions. Gastrointestinal means affecting the stomach or intestines. Extra-intestinal means occurring outside the intestines. And associated conditions means that if someone has one condition, they are more likely to have another condition. It has been found that people who have Celiac Disease are more likely to have other conditions on the associated conditions list, as well as the other way around.