In the context of diagnosing anemia, what does a reticulocyte production index (RPI) help differentiate between?

The reticulocyte production index (RPI) is a calculated value that helps differentiate between hypoproliferative anemias (where the bone marrow does not produce enough red blood cells) and hyperproliferative anemias (where the bone marrow produces red blood cells at a normal or increased rate, but they are lost or destroyed at an increased rate). It adjusts the reticulocyte count for the degree of anemia, providing insight into bone marrow response.