Dehydration-related loss of plasma leads to polycythemia is classified as which type?

Dehydration-related loss of plasma leads to polycythemia is classified as which type?

• A. Primary polycythemia
• B. Secondary polycythemia
• C. Polycythemia Vera
• D. Relative polycythemia

Answer: (B)

The concept here is how polycythemia is classified by what happens to red cell mass versus plasma volume. Dehydration contracts plasma volume, so the concentration of red cells rises even though the total red cell mass hasn’t increased. That makes this a relative polycythemia—hemoconcentration from fluid loss without a true increase in red cell production. Secondary polycythemia, by contrast, involves an actual rise in red cell mass driven by increased erythropoietin (from hypoxia, tumors, or other triggers), not just reduced plasma volume. Primary polycythemia (polycythemia vera) is a clonal overproduction of red cells independent of EPO. So dehydration-related loss of plasma leading to higher hematocrit is best categorized as relative polycythemia.

The concept here is how polycythemia is classified by what happens to red cell mass versus plasma volume. Dehydration contracts plasma volume, so the concentration of red cells rises even though the total red cell mass hasn’t increased. That makes this a relative polycythemia—hemoconcentration from fluid loss without a true increase in red cell production.

Secondary polycythemia, by contrast, involves an actual rise in red cell mass driven by increased erythropoietin (from hypoxia, tumors, or other triggers), not just reduced plasma volume. Primary polycythemia (polycythemia vera) is a clonal overproduction of red cells independent of EPO.

So dehydration-related loss of plasma leading to higher hematocrit is best categorized as relative polycythemia.