Differential Diagnosis
- Single most likely diagnosis
- Autoimmune gastritis: This is the most likely diagnosis given the patient's positive parietal cell antibody test, low iron, and low iron saturation. 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
- Iron deficiency anemia due to chronic blood loss: Although the patient has a positive parietal cell antibody test, it's still possible that she has another source of chronic blood loss, such as menstrual bleeding or gastrointestinal bleeding, that's contributing to her iron deficiency.
- Celiac disease: Celiac disease can cause malabsorption of iron and other nutrients, leading to iron deficiency anemia. The patient's long-standing history of low iron levels could be consistent with celiac disease.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Gastric cancer: Although rare, gastric cancer can cause iron deficiency anemia and should be considered in the differential diagnosis, especially in patients with a long history of unexplained iron deficiency.
- Gastrointestinal bleeding from other sources (e.g., ulcers, vascular ectasias): These conditions can cause chronic blood loss and iron deficiency anemia, and it's essential to rule them out to prevent potentially life-threatening complications.
- Rare diagnoses
- Atrophic gastritis due to other causes (e.g., Helicobacter pylori infection, chronic use of proton pump inhibitors): These conditions can also lead to impaired iron absorption and iron deficiency anemia, although they are less likely given the patient's positive parietal cell antibody test.
- Hereditary iron-refractory iron deficiency anemia: This is a rare genetic disorder that can cause iron deficiency anemia, but it's unlikely given the patient's positive parietal cell antibody test and long-standing history of low iron levels.