A 40-year-old woman who has iron defi ciency anemia began receiving oral iron therapy without…

A 40-year-old woman who has iron defi ciency anemia began receiving oral iron therapy without response. She reports no gastrointestinal tract complaints or heavy menses. She has a normal appetite and reports no weight loss. Th ere is no family history of colon cancer or infl ammatory bowel disease. Fecal occult blood testing of the stool is negative. Which test should be performed next? a. Measurement of serum IgA and IgG tissue transglutaminase antibodies b. Upper endoscopy with small bowel biopsies c. Capsule endoscopy d. Small bowel follow-through e. Stool evaluation for ova and parasites