ASCP Specialist In Hematology (SH) Practice Exam

In the context of alpha thalassemia, as the severity of the condition increases, there is a characteristic change in the mean corpuscular volume (MCV) and the red cell distribution width (RDW). As alpha thalassemia progresses, particularly in its more severe forms, the bodies of affected individuals produce fewer alpha globin chains which leads to the formation of smaller erythrocytes or microcytic anemia. This reduction in the size of the red blood cells results in a decrease in the MCV, which is a measurement of the average volume of a red blood cell. Additionally, the RDW tends to increase in alpha thalassemia due to the presence of a more heterogeneous population of red blood cell sizes. In early stages or with mild forms, the RDW may not vary significantly; however, as the disease severity increases and the body’s compensation mechanisms come into play, the variability in cell size increases, leading to an elevated RDW. Therefore, the increase in RDW reflects the body's attempt to respond to the anemia by producing more red blood cells of varying sizes. Thus, the combination of a decreasing MCV and an increasing RDW with the severity of alpha thalassemia is a key diagnostic feature