Secondary polycythemia is best described by which statement?

• A. Abnormal Clonal Proliferation of RBCs
• B. Decreased RBC Mass
• C. Dehydration Only
• D. Increased Hematocrit as a Response to Another Process

Answer: (D)

Secondary polycythemia happens when the body increases red blood cell production in response to another stimulus, most often due to increased erythropoietin from chronic hypoxia or ectopic EPO production. This raises the red cell mass and hematocrit not because the marrow is inherently overactive, but because it’s being driven by an external signal. It’s different from primary polycythemia, where a clonal bone marrow abnormality causes red cells to multiply independently of EPO. Dehydration can raise the hematocrit by shrinking plasma volume without increasing red cell mass, so it doesn’t describe true secondary polycythemia. A decreased red cell mass would not be polycythemia at all. Thus the description that fits secondary polycythemia is an increased hematocrit as a response to another process.