Differential Diagnosis for Low MCHC with High RDW

• Single most likely diagnosis
  • Iron deficiency anemia: This is the most common cause of low MCHC (mean corpuscular hemoglobin concentration) with a high RDW (red cell distribution width). Iron deficiency leads to a decrease in hemoglobin production, resulting in red blood cells with less hemoglobin than normal, which is reflected by a low MCHC. The high RDW indicates a variation in red blood cell size, which is typical in iron deficiency anemia as the body tries to compensate for the lack of iron by producing red blood cells of varying sizes.
• Other Likely diagnoses
  • Thalassemia: These are genetic disorders affecting hemoglobin synthesis, leading to variable degrees of anemia. Some forms of thalassemia can present with low MCHC due to the underproduction of the hemoglobin chains, and a high RDW due to the presence of red blood cells of different sizes.
  • Anisocytosis (variability in red blood cell size) due to other chronic diseases: Chronic diseases can lead to anisocytosis, which would result in a high RDW. If these diseases also affect iron metabolism or erythropoiesis, they could potentially lead to a low MCHC.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Sideroblastic anemia: A group of disorders characterized by the accumulation of iron in the mitochondria of red blood cell precursors, leading to impaired hemoglobin synthesis. This can result in a low MCHC and, due to the variability in red blood cell production, a high RDW. Sideroblastic anemia can be congenital or acquired, with the latter sometimes being associated with myelodysplastic syndromes or exposure to certain toxins.
  • Hemoglobinopathies (other than thalassemia): Certain hemoglobinopathies can affect the production or structure of hemoglobin, potentially leading to a low MCHC. The presence of red blood cells with abnormal hemoglobin can also lead to a high RDW due to the variability in cell size and hemoglobin content.
• Rare diagnoses
  • Congenital dyserythropoietic anemias: These are a group of rare genetic disorders characterized by ineffective erythropoiesis and distinct morphological abnormalities in erythroblasts. They can present with a low MCHC and a high RDW due to the abnormal production of red blood cells.
  • Other rare genetic disorders affecting hemoglobin synthesis or red blood cell production: There are several rare genetic conditions that can affect the production of hemoglobin or the development of red blood cells, potentially leading to abnormalities in MCHC and RDW.