Differential Diagnosis for Low MCV, MCH, MCHC, Elevated RBC, and RDW

Single Most Likely Diagnosis

• Iron Deficiency Anemia: This condition is characterized by low MCV (mean corpuscular volume), MCH (mean corpuscular hemoglobin), and MCHC (mean corpuscular hemoglobin concentration) due to insufficient iron for hemoglobin production. Elevated RBC (red blood cell) count can occur as the body attempts to compensate for the lack of oxygen delivery, and RDW (red cell distribution width) is elevated due to the variation in red blood cell size.

Other Likely Diagnoses

• Thalassemia: A genetic disorder affecting hemoglobin production, leading to microcytic (low MCV), hypochromic (low MCHC) anemia. Elevated RBC count can be seen in some forms of thalassemia as a compensatory mechanism, and RDW can be elevated due to the variability in red blood cell size.
• Chronic Disease Anemia: Conditions like chronic kidney disease, rheumatoid arthritis, or chronic infections can lead to anemia of chronic disease, which may present with low MCV, MCH, and MCHC. The RBC count might be elevated in some cases as a response to inflammation, and RDW can be increased due to the mixed population of red blood cells.

Do Not Miss Diagnoses

• Polycythemia Vera: Although less common, this myeloproliferative disorder can present with an elevated RBC count. While it typically presents with elevated hematocrit and hemoglobin, in early stages or with co-existing iron deficiency, it might show microcytic indices. The key is not to miss this diagnosis due to its potential for serious complications like thrombosis.
• Sickle Cell Disease: Certain variants can present with microcytic anemia, especially if there's co-existing iron deficiency or other complicating factors. The RDW can be elevated due to the heterogeneity of red blood cell sizes and shapes.

Rare Diagnoses

• Sideroblastic Anemia: A group of disorders characterized by the presence of ringed sideroblasts in the bone marrow. It can present with microcytic, hypochromic anemia, and elevated RBC count in some cases. The RDW can be elevated due to the variability in red blood cell size and hemoglobinization.
• Myelodysplastic Syndromes (MDS): These are a group of disorders caused by poorly formed or dysfunctional blood cells. Some forms of MDS can present with microcytic anemia, elevated RBC count, and an increased RDW due to the dysplastic changes in the bone marrow.