Hello! Thank you for the query. Maroon stool color can indicate blood in stool. Blood in stool can be present with Celiac, however this symptom is not characteristic for this disease. Other possible reasons should be ruled out at first. Blood mixed with stool can be caused by large intestine issues including colon polyp, colon cancer, inflammatory bowels disease. All this conditions lead to low hemoglobin level and can give low ferritine level. Constipation is also characteristic for large intestine disease. You may also have weight loss, bloating, abdominal pain, nausea, loss of appetite. I suggest you to visit your doctor and get scheduled for colonoscopy first. Stool tests should be also done. If you feel that Celiac can be your disease, antibodies should be checked. Hope this will help. Regards.