MKSAP Quiz: A new diagnosis of anemia
A 65-year-old woman is reevaluated following an initial evaluation for anemia. Other than a gradually increasing sense of fatigue, she has no symptoms. Her only other medical problem is autoimmune thyroid disease. What is the most appropriate diagnostic test to perform next?
A 65-year-old woman is reevaluated following an initial evaluation for anemia. Other than a gradually increasing sense of fatigue, she has no symptoms. Her only other medical problem is autoimmune thyroid disease, which is being treated with levothyroxine. Her last screening colonoscopy, done 4 years earlier, was normal.
Physical examination reveals normal vital signs. There is evidence of conjunctival rim pallor. The remainder of the examination, including thyroid and neurologic examinations, is normal.
At the time of her initial evaluation, laboratory studies showed a hemoglobin level of 10 g/dL (100 g/L) and mean corpuscular volume of 104 fL. Serum cobalamin and ferritin levels were low. An antiparietal cell antibody test was positive. Stool testing revealed no evidence of blood.
Which of the following is the most appropriate test to perform next?
A. Capsule endoscopy
B. Glucose hydrogen breath test
C. Serum gastrin measurement
D. Upper endoscopy
MKSAP Answer and Critique
The correct answer is D. Upper endoscopy. This content is available to MKSAP 18 subscribers as Question 40 in the Gastroenterology and Hepatology section. More information about MKSAP is available online.
Upper endoscopy with gastric biopsy is the most appropriate next diagnostic study. The two forms of atrophic gastritis are Helicobacter pylori–associated and autoimmune. H. pylori–associated atrophic gastritis typically resolves with H. pylori eradication, whereas autoimmune atrophic gastritis has no cure. This patient's hematologic findings and positive testing for serum antiparietal antibodies confirm the diagnosis of pernicious anemia and suggest the presence of autoimmune atrophic gastritis. Iron deficiency anemia is a common comorbidity of autoimmune gastritis, as is autoimmune thyroid disease. Autoimmune gastritis is associated with parietal cell loss, reduced gastric acid production, and secondary hypergastrinemia. Hypergastrinemia is associated with an increased risk for the development of gastric carcinoid and adenocarcinoma. It is prudent to perform upper endoscopy and gastric biopsy at the time of pernicious anemia diagnosis to evaluate for these cancers; however, the benefit on ongoing surveillance endoscopy is unclear. Autoimmune-related pernicious anemia and associated iron deficiency anemia are likely to require lifelong vitamin B12 and iron replacement, respectively.
Capsule endoscopy is typically used to evaluate obscure causes of gastrointestinal bleeding. This patient had a normal colonoscopy 4 years earlier, and stool evaluation is negative for blood.
Finally, this patient's iron deficiency anemia is most likely due to atrophic gastritis–related achlorhydria, which decreases iron absorption by impairing the conversion of ferric iron to absorbable ferrous iron; in many patients, iron deficiency precedes vitamin B12 deficiency. Additional testing for iron deficiency beyond upper endoscopy is likely unnecessary.
Although small intestinal bacterial overgrowth (SIBO) can be associated with anemia, the diagnosis is unlikely in this patient with no risk factors or typical symptoms of SIBO; therefore, a glucose breath test to assess for SIBO is likely to be of low yield.
The serum gastrin level is elevated in patients with any form of atrophic gastritis and has no diagnostic or prognostic value in this setting.
Key Point
- Patients with newly diagnosed pernicious anemia should be evaluated for gastric adenocarcinoma and gastric carcinoid with upper endoscopy and gastric biopsy.