Which of the following is a common etiology of secondary polycythemia?

Which of the following is a common etiology of secondary polycythemia?

• A. Dehydration
• B. Iron Deficiency Anemia
• C. Hypoxia From COPD
• D. Polycythemia Vera

Answer: (C)

Secondary polycythemia happens when the body makes more red blood cells in response to low oxygen levels, driven by increased erythropoietin production. In chronic lung diseases like COPD, persistent hypoxemia signals the kidneys to release more erythropoietin, which stimulates the bone marrow to produce more RBCs. This raises hemoglobin and hematocrit to boost oxygen delivery, though it also makes the blood thicker. Dehydration causes relative polycythemia from plasma volume loss, not a true increase in RBC mass. Iron deficiency anemia would reduce red cell mass rather than increase it. Polycythemia vera is a primary, JAK2-driven increase in RBCs with low erythropoietin, not secondary to hypoxia. Therefore, hypoxia from COPD is a classic, common cause of secondary polycythemia.

Secondary polycythemia happens when the body makes more red blood cells in response to low oxygen levels, driven by increased erythropoietin production. In chronic lung diseases like COPD, persistent hypoxemia signals the kidneys to release more erythropoietin, which stimulates the bone marrow to produce more RBCs. This raises hemoglobin and hematocrit to boost oxygen delivery, though it also makes the blood thicker.

Dehydration causes relative polycythemia from plasma volume loss, not a true increase in RBC mass. Iron deficiency anemia would reduce red cell mass rather than increase it. Polycythemia vera is a primary, JAK2-driven increase in RBCs with low erythropoietin, not secondary to hypoxia. Therefore, hypoxia from COPD is a classic, common cause of secondary polycythemia.