GERD and Peptic Ulcer Disease USMLE Step 1 Practice Question
A 62-year-old woman with a 15-year history of gastroesophageal reflux disease treated with omeprazole 40 mg daily presents with a 6-month history of progressive fatigue, paresthesias in her feet, and soreness of her tongue. She denies melena, hematochezia, or weight loss. Vital signs are normal. Laboratory studies show hemoglobin 9.1 g/dL with a mean corpuscular volume of 108 fL, serum cobalamin 185 pg/mL (normal 200-900), and elevated methylmalonic acid. Intrinsic factor antibodies and anti-parietal cell antibodies are both negative. Upper endoscopy demonstrates atrophic changes in the gastric body and fundus with intestinal metaplasia; the antrum appears normal. Which of the following best explains the pathophysiology of this patient's anemia?
Answer choices
- AChronic PPI use reducing gastric acid secretion and B12 malabsorption from food sourcesCorrect answer
- BAutoimmune destruction of gastric parietal cells with secondary loss of intrinsic factor
- CHelicobacter pylori gastritis localized to the gastric antrum causing chronic occult bleeding
- DLong-standing intestinal metaplasia leading to decreased expression of B12 transporters in the terminal ileum
- EPancreatic insufficiency secondary to chronic PPI use impairing cobalamin proteolysis
- FDietary inadequacy of animal protein sources in an elderly patient with poor oral intake
See the full explanation
Get the correct-answer rationale, why each distractor is wrong, the underlying mechanism, and high-yield associations â plus adaptive practice that targets your weak areas â with a free MedBoardPRO account.