"Tear Drops in the Duodenum": Uncommon Cause of Iron Deficiency Anemia in Adults.

A 64-year-old man presented to the internal medicine resident clinic with fatigue and abdominal pain of six-month duration. He did not have diarrhea, hematemesis, melena, or hematochezia. Physical examination was unremarkable. Laboratory findings were consistent with iron deficiency anemia. Upper and lower gastrointestinal (GI) endoscopies revealed normal findings. Duodenal biopsy showed trophozoites (tear-drop-shaped) morphologically consistent with Giardia duodenalis. He was prescribed metronidazole and iron replacement therapy, with a resultant improvement in symptoms as well as lab values at the four-month follow-up visit.