Differential Diagnosis
The patient's laboratory results show a low PTT (25), normal CRP (0.1), normal Anion Gap (4.0), normal osmolality (276), low MCV, and high RDW (15.6). Based on these findings, the differential diagnosis can be categorized as follows:
- Single most likely diagnosis
- Iron deficiency anemia: The low MCV indicates microcytic anemia, and the high RDW suggests a variation in red blood cell size, which is consistent with iron deficiency anemia. The normal CRP and lack of other inflammatory markers make this a likely diagnosis.
- Other Likely diagnoses
- Thalassemia: This genetic disorder can cause microcytic anemia with a high RDW. The low PTT is not directly related to thalassemia, but it does not rule out the diagnosis.
- Anisocytosis (variation in red blood cell size) due to other causes: Other conditions, such as mixed anemia or early stages of vitamin deficiency anemia, can also cause a high RDW and low MCV.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Sickle cell disease: Although less likely, sickle cell disease can cause a high RDW and microcytic anemia. Missing this diagnosis could have severe consequences, as sickle cell disease requires specific management.
- Myelodysplastic syndrome (MDS): MDS can cause a high RDW and low MCV, and it is essential to consider this diagnosis, especially in older adults, as it may require prompt treatment.
- Rare diagnoses
- Other hemoglobinopathies: Rare genetic disorders, such as hemoglobin C or E, can cause microcytic anemia with a high RDW.
- Red blood cell membrane disorders: Conditions like hereditary spherocytosis or elliptocytosis can cause a high RDW and microcytic anemia, although they are less common.