Young children tend to have the more classic signs of celiac disease, including growth problems (failure to thrive, chronic diarrhea/constipation, recurring abdominal bloating and pain, fatigue, and irritability.
Older children and adults tend to have symptoms that are not entirely gastrointestinal in nature. Recent research has demonstrated that only a third of adult patients diagnosed with celiac disease experience diarrhea. Weight loss is also not a common sign. The most common sign of celiac disease in adults is iron deficiency anemia that does not respond to iron therapy.