answered Sep 17, 2009 at 07:57AM
Is it Celiac? Symptoms may include those of irritable bowel syndrome (IBS) with abdominal cramping, intestinal gas, and episodes of both constipation and diarrhea. If Celiac is not diagnosed based on intestinal symptoms, the effects may lead to anemia and vitamin deficiencies with fatigue as a symptom.
Of course is one is aware of the implications of gluten in the diet, even a biopsy may not provide definitive diagnosis.
This is not necessarily an evidence-based answer, but one based on personal experience.