Celiac disease is a condition where an affected individual has a severe immune response when they consume a substance called gluten. Gluten is a protein typically found in foods that have rye, wheat, and barley. The immune response in celiac disease patients affects their small intestine. Over time, the lining of the individual's small intestine becomes too damaged to be able to absorb nutrients properly.
This malabsorption and damage cause the patient to have multiple digestive symptoms, including bloating, diarrhea, pain in the abdomen, nausea, vomiting, constipation, and weight loss. The abdominal pain in affected individuals is not always focal and can radiate to different regions of the abdomen. Therefore, an individual who has celiac disease and intestinal damage may present with pain in the lower left abdomen.