Differential Diagnosis
- Single most likely diagnosis
- Autoimmune gastritis: This is the most likely diagnosis given the patient's low iron levels, low iron saturation, and positive parietal cell antibody test. The presence of parietal cell antibodies is a hallmark of autoimmune gastritis, which can lead to impaired iron absorption and chronic iron deficiency anemia.
- Other Likely diagnoses
- Pernicious anemia: Although the intrinsic factor antibody test is negative, pernicious anemia cannot be completely ruled out. Some patients with pernicious anemia may have negative intrinsic factor antibodies, and the diagnosis can be made based on clinical presentation, low vitamin B12 levels, and response to treatment.
- Iron deficiency anemia due to chronic blood loss: The patient's 15-year history of low iron levels suggests a chronic process, and iron deficiency anemia due to chronic blood loss (e.g., menstrual bleeding, gastrointestinal bleeding) should be considered.
- Do Not Miss
- Celiac disease: This condition can cause malabsorption of iron and other nutrients, leading to chronic iron deficiency anemia. Celiac disease can be associated with autoimmune gastritis, and missing this diagnosis could lead to prolonged morbidity.
- Gastric cancer: Although rare, gastric cancer can cause iron deficiency anemia due to chronic blood loss or malabsorption. A diagnosis of gastric cancer would be life-threatening if missed, and further evaluation (e.g., endoscopy) may be necessary to rule out this condition.
- Rare diagnoses
- Atrophic gastritis: This condition can cause impaired iron absorption and chronic iron deficiency anemia. However, it is less likely than autoimmune gastritis given the patient's positive parietal cell antibody test.
- Helicobacter pylori infection: This infection can cause chronic gastritis and impaired iron absorption, leading to iron deficiency anemia. However, the patient's positive parietal cell antibody test and negative intrinsic factor antibody test make this diagnosis less likely.