Final answer:
An RBC histogram with a higher RDW will show a wider distribution curve, indicative of a greater variation in red blood cell sizes often associated with conditions of anemia. Other diseases like polycythemia vera can affect blood counts but have different effects on RBC histograms.
Step-by-step explanation:
When a red blood cell (RBC) histogram indicates a higher Red Cell Distribution Width (RDW), it suggests greater variability in the size of the RBCs, which is a measure of anisocytosis. Typically, a higher RDW can be seen in conditions such as various types of anemia, where there is a mixed population of both microcytic (smaller) and macrocytic (larger) cells. With a high RDW, the histogram would display a wider distribution curve, indicating an increased spread of cell sizes rather than a narrow, uniform peak that is characteristic of a healthy individual with uniform red blood cell sizes.
Apart from anemias, other conditions like polycythemia vera can also have an effect on the histogram. Polycythemia vera leads to an overproduction of red blood cells, which can raise the viscosity of the blood, causing an elevation in both the red blood cell count and hematocrit levels. However, it is primarily conditions that lead to heterogeneous RBC populations that will typically cause a noticeable change in the RDW on a histogram.