Differential Diagnosis for Low MCH, MCHC, and Elevated RDW

Single Most Likely Diagnosis

• Iron Deficiency Anemia: This is the most common cause of low MCH (Mean Corpuscular Hemoglobin) and MCHC (Mean Corpuscular Hemoglobin Concentration) along with an elevated RDW (Red Cell Distribution Width). The low MCH and MCHC indicate that the red blood cells have less hemoglobin than normal, and the elevated RDW suggests a variation in red blood cell size, which is typical in iron deficiency anemia as the body produces red blood cells with varying amounts of hemoglobin.

Other Likely Diagnoses

• Thalassemia: These are genetic disorders affecting hemoglobin production, leading to variable degrees of anemia. Some forms of thalassemia can present with low MCH and MCHC due to the underproduction of the hemoglobin chains, and an elevated RDW due to the presence of red blood cells of varying sizes.
• Anemia of Chronic Disease: This condition can also lead to low MCH and MCHC, although the RDW may not always be elevated. However, in some cases, especially when there's a component of iron deficiency or when the disease process affects erythropoiesis, an elevated RDW can be seen.
• Sideroblastic Anemia: A group of disorders characterized by the presence of ringed sideroblasts in the bone marrow. These conditions can lead to microcytic, hypochromic anemia (low MCH and MCHC) with an elevated RDW due to the variability in red blood cell size.

Do Not Miss Diagnoses

• Copper Deficiency: Although rare, copper deficiency can cause a microcytic, hypochromic anemia similar to iron deficiency, with low MCH and MCHC and an elevated RDW. It's crucial not to miss this diagnosis as it requires specific treatment.
• Vitamin Deficiency (B6, B12, or Folate): While these deficiencies typically cause macrocytic anemia, in some cases, especially when there's a mixed picture or an early stage of deficiency, they might present with microcytic indices and an elevated RDW.

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 ones with low MCH, MCHC, and an elevated RDW.
• Lead Poisoning: Can cause a microcytic, hypochromic anemia with basophilic stippling of red blood cells and may present with an elevated RDW.
• Chronic Lead Exposure with Iron Deficiency: This combination can exacerbate the microcytic, hypochromic anemia picture and is an important consideration in certain occupational or environmental exposures.