What condition is characterized by diarrhea with macrocytic anemia and elevated liver function tests (LFTs)?

The condition characterized by diarrhea, macrocytic anemia, and elevated liver function tests is celiac disease. This autoimmune disorder occurs due to an inappropriate immune response to gluten, leading to intestinal damage and malabsorption. The malabsorption results in diarrhea, weight loss, and nutrient deficiencies, including vitamin B12 and folate, which can cause macrocytic anemia.

Elevated liver function tests can occur in celiac disease because of associated liver conditions, particularly nonalcoholic fatty liver disease or autoimmune hepatitis, which can accompany the primary celiac condition. This combination of gastrointestinal symptoms alongside anemia and liver function abnormalities strongly points to celiac disease as the underlying cause.

In contrast, conditions like Crohn's disease and ulcerative colitis primarily involve inflammation of the bowel, and while they can also lead to diarrhea and some anemia, they do not typically present with macrocytic anemia as a core feature, nor are they commonly associated with elevated liver function tests in the same manner as celiac disease. Irritable bowel syndrome does not directly cause macrocytic anemia or elevated liver function tests, as it is a functional gastrointestinal disorder rather than one that leads to significant physiological damage or nutrient absorption issues.