RDW (Red Cell Distribution Width) is often, but not always, high in thalassemia.
While a high RDW is commonly associated with iron deficiency anemia (present in over 90% of cases), it's only elevated in about 50% of individuals with thalassemia. This difference in RDW elevation can be a clue in differentiating between the two conditions, although further testing is always necessary for a definitive diagnosis. The RDW reflects the variation in red blood cell size (anisocytosis). In thalassemia, the body produces smaller than normal red blood cells (microcytosis), but the variation in size may not be as dramatic as seen in iron deficiency.
Here's a breakdown:
-
Iron Deficiency Anemia: Typically presents with a high RDW because iron deficiency leads to a greater variation in red blood cell size as the bone marrow struggles to produce normal cells.
-
Thalassemia: May or may not present with a high RDW. While the red blood cells are often smaller (microcytic), the consistency in their smaller size means the RDW isn't always elevated. The degree of RDW elevation in thalassemia can vary depending on the specific type and severity of the condition.
Therefore, a normal RDW does not rule out thalassemia. Additional blood tests, such as hemoglobin electrophoresis, are needed to confirm the diagnosis.
