Differential Diagnosis
- Single most likely diagnosis + Iron deficiency anemia: The patient's laboratory results show a low hemoglobin level (5.1 g/dL), low hematocrit (18.8%), and a history of GI bleed with a positive guaiac test, which suggests chronic blood loss leading to iron deficiency anemia. The microcytic anemia (MCV 78.3) and low MCHC (27.1) also support this diagnosis.
- Other Likely diagnoses + Anemia of chronic disease: Although the patient's CT abdomen shows no evidence of acute intraabdominal pathology, the presence of a GI bleed and possible underlying chronic disease (e.g., inflammatory bowel disease, cancer) could contribute to anemia of chronic disease. + Mixed anemia (iron deficiency and anemia of chronic disease): Given the patient's complex presentation, it's possible that both iron deficiency and anemia of chronic disease are contributing to the anemia.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.) + Upper GI malignancy: Although the CT abdomen shows no evidence of acute intraabdominal pathology, it's essential to consider the possibility of an upper GI malignancy, such as gastric or esophageal cancer, which could cause chronic bleeding and anemia. + Lower GI malignancy: Similarly, a lower GI malignancy, such as colorectal cancer, could also cause chronic bleeding and anemia. + Angiodysplasia or vascular malformations: These conditions can cause chronic GI bleeding and anemia, especially in older adults.
- Rare diagnoses + Sideroblastic anemia: This rare condition is characterized by the presence of ringed sideroblasts in the bone marrow and can cause microcytic anemia. + Thalassemia: Although less likely, thalassemia could be considered in the differential diagnosis, especially if the patient has a family history or is of Mediterranean or Asian descent. + Chronic bleeding from a Meckel's diverticulum: This rare condition can cause chronic GI bleeding and anemia, especially in younger adults.