Differential Diagnosis for Anemia with High RBC, Low MCV, Low MCHC, and High RDW

• Single Most Likely Diagnosis

  • Iron Deficiency Anemia: This condition is characterized by a decrease in the mean corpuscular volume (MCV) and mean corpuscular hemoglobin concentration (MCHC), indicating microcytic hypochromic anemia. The high red blood cell distribution width (RDW) suggests a variation in red blood cell size, which is common in iron deficiency anemia due to the gradual depletion of iron stores affecting hemoglobin synthesis and leading to a range of cell sizes.

• Other Likely Diagnoses

  • Thalassemia: These genetic disorders affect hemoglobin production, leading to microcytic anemia (low MCV) and can have a high RDW due to the variability in red blood cell size. However, the MCHC is often low, and there's typically an increase in RBC count as the body compensates for the decreased oxygen-carrying capacity of each cell.
  • Anisopoikilocytosis (Variation in Size and Shape of Red Blood Cells): This can be seen in various conditions, including but not limited to, iron deficiency anemia, and can result in a high RDW. The presence of a high RBC count, low MCV, and low MCHC would need to be correlated with the clinical context and possibly further testing to differentiate from other causes.

• Do Not Miss Diagnoses

  • Mixed Anemia (Iron Deficiency and Vitamin Deficiency): It's crucial not to miss a mixed anemia, especially if there's a component of vitamin B12 or folate deficiency, as these require different treatments. A high RDW can be indicative of a mixed population of red blood cells, reflecting different deficiencies.
  • Sideroblastic Anemia: Although less common, this condition can present with microcytic hypochromic anemia and increased RDW. It's essential to consider this diagnosis, especially if there's a failure to respond to iron supplementation or if other clinical features suggest a different underlying pathology.

• Rare Diagnoses

  • Myelodysplastic Syndromes (MDS): These are a group of disorders caused by poorly formed or dysfunctional blood cells, which can lead to various types of anemia, including those with high RDW and microcytic hypochromic indices. MDS is more common in older adults and can have a varied presentation.
  • Chronic Disease Anemia with Iron Sequestration: In chronic diseases like rheumatoid arthritis or chronic infections, there can be an element of iron sequestration leading to a microcytic hypochromic anemia picture, although the RDW might not always be as high as in iron deficiency anemia.