A 56-year-old woman comes to the office due to epigastric abdominal pain for the past year. The pain worsens after eating and is described as crampy, intermittent, and nonradiating. The patient has had bloating and nausea but no unexpected weight loss, vomiting, constipation, diarrhea, melena, hematochezia, or changes in bowel habits. Medical history is significant for hypertension and hypothyroidism. Family history is unremarkable. She does not use tobacco or alcohol. Temperature is 37.5 C (99.5 F), blood pressure is 142/67 mm Hg, pulse is 80/min, and respirations are 14/min. The patient is not in acute distress. Heart and lung sounds are unremarkable. The abdomen is mildly tender to palpation in the epigastrium without rebound, guarding, or distension. Laboratory results are as follows: Which of the following is the most likely diagnosis in this patient?

Question

A 56-year-old woman comes to the office due to epigastric abdominal pain for the past year.  The pain worsens after eating and is described as crampy, intermittent, and nonradiating.  The patient has had bloating and nausea but no unexpected weight loss, vomiting, constipation, diarrhea, melena, hematochezia, or changes in bowel habits.  Medical history is significant for hypertension and hypothyroidism.  Family history is unremarkable.  She does not use tobacco or alcohol.  Temperature is 37.5 C (99.5 F), blood pressure is 142/67 mm Hg, pulse is 80/min, and respirations are 14/min.  The patient is not in acute distress.  Heart and lung sounds are unremarkable.  The abdomen is mildly tender to palpation in the epigastrium without rebound, guarding, or distension.  Laboratory results are as follows:  Which of the following is the most likely diagnosis in this patient?

Quizplus · Accepted Answer

This patient with hypothyroidism, chronic postprandial abdominal pain, and macrocytic anemia (ie, mean corpuscular volume >100 µm³) likely has autoimmune metaplastic atrophic gastritis (AMAG). AMAG is an autoimmune disorder that affects women more frequently than men; patients with other autoimmune conditions (eg, type 1 diabetes mellitus, autoimmune thyroid disease) are at increased risk. AMAG is characterized by the presence of antibodies toward parietal cells, resulting in atrophy and metaplasia of the gastric corpus, hypochlorhydria, and unchecked gastrin production; and toward intrinsic factor, resulting in vitamin B₁₂ deficiency. Therefore, the diagnosis should be suspected in patients with macrocytic anemia (due to vitamin B₁₂ deficiency) who have suggestive epidemiologic characteristics (eg, female, autoimmune conditions) and gastrointestinal features. Patients often develop dyspepsia with postprandial abdominal pain, bloating, nausea, heartburn, or regurgitation; the pathophysiology may be related to changes in gastroduodenal motility, visceral sensitivity, or acid secretion. Other laboratory findings include elevated serum gastrin levels; iron deficiency anemia may occur as hypochlorhydria leads to reduced iron bioavailability. Because AMAG is associated with an increased risk for gastric adenocarcinoma and neuroendocrine tumors, routine surveillance endoscopy is indicated. (Choices B and E) Functional dyspepsia can present with postprandial abdominal pain and bloating, whereas irritable bowel syndrome leads to changes in bowel frequency and/or caliber along with abdominal cramps. Both diseases are functional disorders and are not associated with laboratory abnormalities; the presence of anemia (macrocytic or otherwise) requires workup for an alternative diagnosis. (Choice C) Gastroparesis can cause postprandial abdominal pain, but vomiting and early satiety would also be expected. It is more common in patients with uncontrolled diabetes or scleroderma and in chronic opiate users. Macrocytic anemia would be atypical. (Choice D) Helicobacter pylori is a risk factor for peptic ulcer disease, which presents with postprandial abdominal pain and gastrointestinal bleeding. It can cause microcytic anemia due to iron deficiency, but macrocytosis would be unexpected. (Choice F) Small intestinal bacterial overgrowth (SIBO) can be caused by small bowel dysmotility (eg, scleroderma, diabetes). SIBO can cause macrocytosis due to bacterial consumption of vitamin B₁₂; however, this diagnosis is unlikely in the absence of diarrhea. Educational objective: Autoimmune atrophic gastritis is an autoimmune disorder resulting in the formation of antibodies toward parietal cells (resulting in hypochlorhydria and unchecked gastrin production) and intrinsic factor (resulting in B₁₂ deficiency). Common manifestations include postprandial abdominal pain, bloating, elevated serum gastrin levels, and macrocytic anemia. References: Upper gastrointestinal symptoms in autoimmune gastritis: a cross-sectional study. (http://www.ncbi.nlm.nih.gov/pubmed/28072728)

A 56-Year-Old Woman Comes to the Office Due to Epigastric